Introduction to Computing CS101 book HANDOUTS in pdf
Handouts | Lectures | Contents | Books
Handouts | Lectures | Contents | Books
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
1
Table of Contents:
Lecture 1 .......................................................................................................... 9
Introduction ..................................................................................................... 9
Lecture 2 ........................................................................................................ 13
Evolution of Computing ................................................................................. 13
2.2 The “Turing test” ........................................................................... 13
2.3 Vacuum Tube – 1904: ...................................................................... 13
2.4 ABC – 1939 ..................................................................................... 14
2.6 ENIAC – 1946: ................................................................................ 14
2.7 Transistor – 1947............................................................................. 14
2.8 Floppy Disk – 1950.......................................................................... 14
2.9 UNIVAC 1 – 1951 ............................................................................ 14
2.11 ARPANET – 1969 ....................................................................... 15
2.12 Intel 4004 – 1971 .......................................................................... 15
2.13 Altair 8800 – 1975......................................................................... 15
2.14 Cray 1 – 1 976 .............................................................................. 16
2.15 IBM PC – 1981 ............................................................................ 16
2.16 Apple Macintosh – 1984............................................................... 16
2.17 World Wide Web -1989 ................................................................ 16
2.18 Quantum Computing with Molecules.......................................... 17
Lecture 3 ....................................................................................................... 18
3.1 Browser .......................................................................................... 18
3.2 URL................................................................................................... 18
3.3 What is a Web site?............................................................................. 18
3.4 What is Home Page of a web site? ...................................................... 19
3.5 Who invented the Web & Why? .......................................................... 19
3.6 Future of the Web: Semantic Web....................................................... 20
3.7 Useful Web page ................................................................................ 20
Lecture 4 ........................................................................................................ 21
4.1 Computer Types According to Capability............................................ 21
4.2 Supercomputers ................................................................................. 21
4.3 Mainframe Computers........................................................................ 21
4.4 Servers / Minicomputers .................................................................... 21
4.5 Desktops............................................................................................ 21
4.6 Portables............................................................................................ 21
4.7 Ranking w.r.t. installed number.......................................................... 22
4.8 All computers have the following essential hardware components:....... 22
4.9 Input Devices..................................................................................... 23
4.10 What is Port? .................................................................................... 24
4.11Many Types of Ports .......................................................................... 24
4.12 Processor.......................................................................................... 24
4.13 Memory/Storage .............................................................................. 24
4.14 Classifying Memory/Storage............................................................. 25
4.15 Output Devices................................................................................. 25
4.16 Modem............................................................................................. 25
1.1
1.2
1.3
2.5 Harvard Mark 1 – 1943:.................................................................... 14
2.10 Compiler - 1952 ........................................................................... 15
Charles Babbage (1791-1871)................................................................. 9
The Analytical Engine.......................................................................... 9
Ada, Countess of Lovelace(1815-52) ...................................................... 9
1.4 Course Contents & Structure .............................................................. 10
2.1 Turing Machine – 1936.................................................................... 13
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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Lecture 5........................................................................................................27
5.1 PC Parts..............................................................................................27
5.2 Inside of the CPU ...............................................................................27
5.3 The Processor Module ........................................................................27
Lecture 6.........................................................................................................28
6.1 To develop your personal Web page ....................................................28
Lecture 7.........................................................................................................31
7.1 Microprocessor ...................................................................................31
7.2 Integrated Circuits..............................................................................31
7.3 Devices...............................................................................................31
7.4 Microprocessor system.......................................................................33
7.5 Micro-controllers ................................................................................33
7.6 The Main Memory Bottleneck ............................................................33
7.7 Cache .................................................................................................33
7.8 Microprocessors Building Blocks ........................................................34
Lecture 8.........................................................................................................39
Binary Numbers & Logic Operations ..............................................................39
8.1 Why binary .........................................................................................42
8.2 Boolean Logic Operations...................................................................43
8.3 Truth Table for the XOR Operation ....................................................45
8.4 STRATEGY: Divide & Conquer.........................................................45
Lecture 9.........................................................................................................47
HTML Lists & Tables (Web Development Lecture 3).....................................47
9.1 Single Tags .........................................................................................47
9.2 Types of Lists .....................................................................................52
9.3 Ordered List Types.............................................................................52
9.4 Useful URL ........................................................................................57
Lecture 10 .......................................................................................................59
Computer Software..........................................................................................59
10.1 Machine Language............................................................................59
10.2 Language Translators........................................................................59
10.3 Software Development.......................................................................59
10.4 Major Types of SW............................................................................60
10.5 System SW are programs that … ........................................................60
10.6 Operating System..............................................................................60
10.7 Utilities: ............................................................................................61
10.8 Language Translators........................................................................61
10.9 Device Drivers...................................................................................61
10.10 Application SW ................................................................................61
10.11 Another way of classifying SW ..........................................................62
10.12 Who Owns Software? .......................................................................62
10.13 Main types of SW licensees ..............................................................62
10.14 Proprietary SW License ....................................................................62
10.15 Freeware SW License .......................................................................63
10.16 Open-Source SW License .................................................................63
10.17 Shareware SW License .....................................................................63
10.18 Trialware .........................................................................................63
Lecture 11........................................................................................................65
Operating Systems ..........................................................................................65
11.1 Why Have OSes? ...............................................................................65
11.2 Core Tasks of an OS ..........................................................................65
11.3 OS Components ................................................................................66
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11.4 Kernel ............................................................................................... 67
11.5Types of OS’es ................................................................................... 67
11.6 Another Way of Classifying................................................................ 67
11.7 How many different OS’es are there?................................................. 67
11.8 Comparing Popular OS’es ................................................................. 68
Lecture 12....................................................................................................... 69
Interactive Forms (Web Development Lecture 4)............................................ 69
12.1 Server-Side Scripts............................................................................. 71
12.2 Checkbox Input Element .................................................................. 76
12.3 Radio Button Input Element............................................................. 77
12.4 Select from a (Drop Down) List......................................................... 78
12.5 File Upload Input Element ............................................................... 79
Lecture 13....................................................................................................... 81
Application Software....................................................................................... 81
13.1 Two Major Types of Software ............................................................ 81
13.2 Application Software ......................................................................... 81
13.3 Classification According to the Mode ................................................ 81
13.4 Classification According to Application Area ..................................... 81
13.5 Scientific/Engineering/Graphics Apps ............................................. 81
13.6 Scientific SW..................................................................................... 82
13.7 Engineering SW................................................................................ 82
13.8 Graphics & Animation SW (1) ........................................................... 82
13.9 Business Applications ....................................................................... 82
13.10 E-Commerce Software..................................................................... 82
13.11 ERP (Enterprise Resource Planning) SW ......................................... 83
13.12 DSS (Decision Support Systems) SW................................................ 83
13.13 Productivity SW............................................................................... 83
13.14 Word Processors.............................................................................. 83
13.15 Web Page Development SW............................................................. 83
13.16 Spreadsheet SW (1) .......................................................................... 83
13.17 Spreadsheet SW (2).......................................................................... 83
13.18 Presentation Development SW......................................................... 83
13.19 Small-Scale Databases SW (1) .......................................................... 84
13.20 Small-Scale Databases SW (2).......................................................... 84
13.21 Productivity SW Suites..................................................................... 84
13.22 Document-Centered Computing (DCC) - 1 ...................................... 84
13.23 Document-Centered Computing (DCC) - 2...................................... 84
13.24 Entertainment SW........................................................................... 84
13.25 Music & Video Players .................................................................... 84
13.26 Music Generation & Movie Editing SW........................................... 84
13.27 Games ............................................................................................ 84
13.28 Educational SW .............................................................................. 85
13.29 Electronic Encyclopedias ................................................................ 85
13.30 On-Line Learning ........................................................................... 85
13.31 Interactive CD’s .............................................................................. 85
13.32 Attributes of Good Application Software .......................................... 85
13.33 Most Popular Application Software Categories................................. 85
Lecture 14....................................................................................................... 87
Word Processing............................................................................................. 87
14.1 Word Processor................................................................................. 87
14.2 Types: WYSIWYG-based & Markup-based ....................................... 88
14.3 Desktop Publishing (DTP) ............................................................... 88
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14.4 Word Processors for the Web .............................................................88
14.5 Let’s try to use MS Word for creating a CV.........................................90
Lecture 15 .......................................................................................................91
More on Interactive Forms (Web Development Lecture 5) ..............................91
15.1 Single-Line Text Input Field..............................................................91
15.2 Password Input Field ........................................................................91
15.3 Hidden Input ....................................................................................91
15.4 Checkbox Input Element...................................................................91
15.5 Radio Button Input Element .............................................................91
15.6 File Upload Input Element ................................................................91
15.7 Reset Button Input Element ..............................................................92
15.8 Submit Button Input .........................................................................92
15.9 Multi-Line Text Input Area ...............................................................92
15.10 Select from a (Drop Down) List........................................................92
15.11 Client-Side Scripting is a viable alternate ..........................................94
15.12 Server-Side Scripts: Review...............................................................94
15.13 Why JavaScript? ...............................................................................96
Lecture 16 .......................................................................................................99
Algorithms......................................................................................................99
16.1 Algorithm for Decimal-to-Binary Conversion ...................................100
16.2 Algorithm (Better Definition) ..........................................................100
16.3 Why Algorithms are Useful?.............................................................101
16.4 Analysis of Algorithms.....................................................................101
16.5 Al-Khwarzmi ...................................................................................101
16.6 Greedy Algorithm............................................................................102
16.7 Deterministic Algorithm (1) .............................................................102
16.8 Randomized Algorithm (1) ..............................................................102
16.9 Randomized Algorithm (2) ..............................................................102
16.10 Deterministic Algorithm (2) ...........................................................102
16.11 Heuristic........................................................................................102
16.12 The Brute Force Strategy (1)...........................................................103
16.13 The Brute Force Strategy (2) ..........................................................103
16.14 A Selection of Algorithmic Application Areas..................................103
16.15 Flowchart ......................................................................................104
Lecture 17 .....................................................................................................106
Algorithms II ................................................................................................106
17.1 Algorithm Building Blocks ..............................................................106
17.2 Solution in Pseudo Code..................................................................108
17.3 Tips on Writing Good Pseudo Code.................................................108
17.4 Pros and Cons of Flowcharts (1).......................................................117
17.5 Pros and Cons of Flowcharts (2) ......................................................117
17.6 Pros and Cons of Pseudo Code (1) ...................................................117
17.7 Pros and Cons of Pseudo Code (2) ...................................................117
Lecture 18 .....................................................................................................118
Objects, Properties, Methods (Web Development Lecture 6).........................118
18.1 New Concept: Client-Side Scripts ....................................................119
18.2 Advantages of Client-Side Scripting .................................................119
18.3 Disadvantages.................................................................................119
18.4 JavaScript........................................................................................119
18.5 Client-Side JavaScript ......................................................................120
18.6 Properties........................................................................................121
18.7 Event Handlers ...............................................................................128
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Lecture 19..................................................................................................... 129
Programming Languages.............................................................................. 129
19.1 Batch Programs .............................................................................. 129
19.2 Event-Driven Programs .................................................................. 129
19.3 Types of Prog. Languages............................................................... 130
19.4 Programming SW Development ...................................................... 131
19.5 Object Oriented Design .................................................................. 131
19.6 Structured Design........................................................................... 131
19.7 Object-Oriented Languages............................................................ 132
Lecture 20 .................................................................................................... 133
SW Development Methodology..................................................................... 133
Lecture 21..................................................................................................... 142
Data Types & Operators (Web Development Lecture 7) ............................... 142
21.1 JavaScript Data Types.................................................................... 143
21.2 Declaring Variables........................................................................ 144
21.3 JavaScript Operators ...................................................................... 148
21.4 Comparison Operators.................................................................... 148
21.5 Logical Operators .......................................................................... 148
21.6 Elements of JavaScript Statements ................................................. 149
Lecture 22 .................................................................................................... 151
Spreadsheets................................................................................................. 151
22.1 Business Plan for a New Software Development Company .............. 151
22.2 The Structure of A Spreadsheet ....................................................... 152
22.3 Goal Seek ....................................................................................... 154
Lecture 23 .................................................................................................... 158
Flow Control & Loops (Web Development Lecture 8).................................. 158
JavaScript Variables are Dynamically Typed .......................................... 158
Lecture 24 .................................................................................................... 166
Design Heuristics......................................................................................... 166
24.1 Heuristic ........................................................................................ 166
24.2 System............................................................................................ 166
24.3 System Architecture........................................................................ 166
24.4 Heuristics for system architecting ................................................... 166
Lecture 25 .................................................................................................... 170
Web Design for Usability .............................................................................. 170
25.2 SPEED: ......................................................................................... 170
25.3 Elements of Website Design: .......................................................... 171
25.4 Website Navigation: ....................................................................... 171
25.5 A Few Navigation Design Heuristics: ............................................. 171
25.6 Navigation Design Heuristics (contd.):........................................... 171
25.7 Good designs assist the user in recovering from errors..................... 173
25.8 Assisting the User Recover from Errors: .......................................... 173
25.9 A few constructive recommendations .............................................. 173
25.10 Making Display Elements Legible:................................................ 175
25.11 Ensuring Text is Readable:............................................................ 175
25.12 Using Pictures & Illustrations: ...................................................... 176
25.13 Using Motion................................................................................ 176
Arrays (Web Development Lecture 9) ........................................................... 177
26.1 Arrays in JavaScript......................................................................... 178
26.2 Array Identifiers................................................................................ 180
26.3 The ‘length’ Property of Arrays ....................................................... 181
26.4 Array Methods: sort( ) 26.5 Sorts the elements in alphabetical order . 181
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26.6 Array Methods: reverse( ) 26.7 Reverses the order of the elements ....181
26.7 Pseudo Code...................................................................................182
Lecture 27 .....................................................................................................185
Computer Networks......................................................................................185
27.1 Private Networks.............................................................................186
27.2 Public Networks .............................................................................186
27.3 VPN: Virtual Private Network (1) ....................................................187
27.4 Network Topologies .......................................................................188
27.5 Networking Protocols .....................................................................190
27.6 Types of Communication Channels.................................................191
27.7 Network Security ............................................................................191
Lecture 28 .....................................................................................................193
Introduction to the Internet ...........................................................................193
28.1 Internet: Network of Networks ...........................................................196
28.2 Internet Networking Protocols ........................................................196
Lecture 29 .....................................................................................................199
Functions & Variable Scope (Web Development Lecture 10) .........................199
29.1 Function .........................................................................................199
29.2 Advantages of Functions .................................................................200
29.3 Function Identifiers ........................................................................201
29.4 Arguments of a Function.................................................................201
29.5 Event Handlers...............................................................................203
29.6 Scope of Variable ............................................................................204
Lecture 30 .....................................................................................................209
Internet Services............................................................................................209
30.1 Internet Addressing.........................................................................210
30.2 DNS: Domain Name System...........................................................210
30.3 Internet Services .............................................................................210
30.3 How does an eMail system work? ....................................................213
30.4 Using Instant Messaging ................................................................215
30.5 VoIP: Voice over IP.........................................................................220
Lecture 31 .....................................................................................................221
Developing Presentations..............................................................................221
31.1 Presentations: ..................................................................................221
31.2 The Structure of A Presentation: ......................................................224
31.3 Presentation Development SW:........................................................224
Lecture 32 .....................................................................................................226
Event Handling (Web Development Lecture 11)............................................226
32.1 What is Event Handling? ....................................................................228
32.2 In-Line JavaScript Event Handling :................................................229
Lecture 33 .....................................................................................................234
Graphics & Animation ..................................................................................234
33.1 Computer Graphics: ........................................................................235
33.2 Displaying Images: .........................................................................235
33.3 Pixel Colors :...................................................................................235
33.4 Color Mapping : ..............................................................................235
33.5 Dithering: .......................................................................................236
33.6 Aliasing: .........................................................................................236
33.7 Anti-Aliasing:..................................................................................236
33.8 Graphics File Formats: ....................................................................237
33.9 Vector or Object-Oriented Graphics: ...............................................237
33.10 Bit-Mapped or Raster Graphics:.....................................................237
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33.11 File Formats Popular on the Web (1): ............................................. 237
33.12 Image Processing:......................................................................... 237
33.13-D Graphics: .................................................................................. 238
33.14 Animation: .................................................................................... 238
Lecture 34 .................................................................................................... 240
Intelligent Systems ....................................................................................... 240
34.1 (Artificial) Intelligent Systems: ........................................................ 241
34.2 Fuzzy Logic: .................................................................................. 242
34.3 Robotics: ........................................................................................ 244
Lecture 35 .................................................................................................... 245
Mathematical Methods (Web Development Lecture 12)................................ 245
35.1 Problems & Solutions: .................................................................... 246
35.2 Mathematical Functions in JavaScript: ............................................ 248
Lecture 36 .................................................................................................... 251
Data Management ........................................................................................ 251
36.1 BholiBooks.com : ........................................................................... 252
36.2 Issues in Data Management:........................................................... 252
36.3 DBMS : .......................................................................................... 253
36.4 OS Independence: .......................................................................... 254
36.5 The Trouble with Flat-File Databases: ............................................ 257
Lecture 37 .................................................................................................... 259
Database Software ........................................................................................ 259
37.1 RDBMS.......................................................................................... 262
37.2 Some Terminology ......................................................................... 263
Lecture 38 .................................................................................................... 264
String Manipulations (Web Development Lecture 13) ................................... 264
38.1 String Manipulation in JavaScript.................................................... 267
Lecture 39 .................................................................................................... 274
Cyber Crime ................................................................................................. 274
39.1 07 February 2000 ............................................................................. 275
39.2 DoS Attack: A Cyber Crime............................................................ 276
39.3 More cybercrimes … ...................................................................... 276
39.4 Viruses ........................................................................................... 277
39.5 Other Virus-Like Programs............................................................. 278
Lecture 40 .................................................................................................... 279
Social Implications of Computing ................................................................. 279
40.1 Introduction ................................................................................... 280
40.2 Powerful Global Corporations ......................................................... 280
40.3 The Network Organization............................................................. 280
40.4 Working from Home ...................................................................... 281
40.5 From Mass- to Personalized-Marketing .......................................... 281
40.6 The Political Process ...................................................................... 282
Lecture 41..................................................................................................... 284
Images & Animation (Web Development Lecture 14) ................................... 284
41.1 Images in JavaScript ....................................................................... 286
41.2 Flash Animation ............................................................................. 293
Lecture 42 .................................................................................................... 294
The Computing Profession ........................................................................... 294
42.1 IT: Information Technology............................................................ 295
42.2 Organization: A Collection of Teams .............................................. 296
Lecture 43 .................................................................................................... 302
The Future of Computing ............................................................................. 302
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Lecture 44 .....................................................................................................308
Programming Methodology (Web Development Lecture 15) .........................308
44.1 Design Guidelines ...........................................................................309
44.2 Coding Guidelines ..........................................................................309
44.3 Guidelines for Developing Short Programs ......................................310
44.4 Design & Code Reviews..................................................................311
44.5 Testing & Debugging .....................................................................312
44.6 Helpful Editors ...............................................................................314
Lecture 45 .....................................................................................................316
Review & Wrap-Up .......................................................................................316
Course Objectives ..................................................................................323
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Lecture 1
Introduction
1.1. Charles Babbage (1791-1871)
Creator of the Analytical Engine - the first general-purpose digital computer (1833)
The Analytical Engine was not built until 1943 (in the form of the Harvard Mark I)
1.2. The Analytical Engine
A programmable, mechanical, digital machine
Could carryout any calculation
Could make decisions based upon the results of the previous calculation
Components: input; memory; processor; output
1.3. Ada, Countess of Lovelace(1815-52)
Babbage: the father of computing
Ada: the mother?
Wrote a program for computing the Bernoulli’s sequence on the Analytical Engine -
world’s 1st computer program
Ada: A programming language specifically designed by the US Dept of Defense for
developing military applications was named Ada to honor her contributions towards
computing
A lesson that we all can learn from Babbage’s Life
Charles Babbage had huge difficulties raising money to fund his research
As a last resort, he designed a clever mathematical scheme along with Ada, the Countess
of Lovelace
It was designed to increase their odds while gambling. They bet money on horse races
to raise enough money to support their research experiments
Guess what happened at the end? The lost every penny that they had.
Fast
Bored
Storage
Here is a fact:
In 1997 Deep Blue, a supercomputer designed by IBM, beat Gary Kasparov, the World
Chess Champion
That computer was exceptionally fast, did not get tired or bored. It just kept on
analyzing the situation and kept on searching until it found the perfect move from its
list of possible moves …
Goals for Today:
To develop an appreciation about the capabilities of computing
To find about the structure & policies of this course
It could analyze up to 300 billion chess moves in
three minutes
Introduction to Computing –CS101 VU
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CS101 Introduction to Computing
1.4 Course Contents & Structure
Course Objectives
To build an appreciation for the fundamental concepts in computing
To achieve a beginners proficiency in Web page development
To become familiar with popular PC productivity software
Readings
W
e
e
k
Lecture 1 Lecture
2
Lecture
3
Web
Dev
UC JS
Assignment
1
2
3
4
5
6
7
8 Midterm
Exam
9
10
11
12
13
14
15
Finals Week
Intro to computing
Evolution of computing
Computer organization
Building a PC
Microprocessors
Binary numbers & logic
Computer software
Operating systems
Application software
Algorithms
Flowcharts
Programming languages
Development methodology
Design heuristics
Web design for usability
Computer networks
Intro to the Internet
Internet services
Graphics & animation
Intelligent systems
Data management
Cyber crime
Social implications
The computing profession
The future of computing
Fundamental concepts
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Web page development
Web Development
The World Wide Web
Making a Web page
Lists & tables
Interactive forms
Objective & methods
Data types & operators
Flow control & loops Arrays
Built-in functions
User-defined functions
Events handling
String manipulation
Images & graphics
Programming methodology
Productivity Applications
Word processor
Spreadsheet
Presentation software
Database
Instructor:
Altaf Khan
Course Web Page:
UC - Understanding Computers (2000 ed.)
JS - Learn JavaScript in a Weekend
Reading Assignments
Please make sure to read the assigned material for each week before the commencement
of the corresponding week
Reading that material beforehand will help you greatly in absorbing with ease the matter
discussed during the lecture
Check your e-mail often for announcements related to this and other VU courses
Marks
distribution …
Assignments (15%)
Almost one every week, 13 in all
No credit for late submissions
The lowest 2 assignment grades will be dropped
Midterm Exam (35%)
During the 8th week
Duration: One hour
Will cover all material covered during the first seven weeks
Final Exam (50%)
During the 16th week
Will cover the whole of the course with a slight emphasis on the material covered after
the midterm exam
Duration: 2 hours
First Assignment
cs101@vu.edu.pk
http://vulms.vu.edu.pk/
Textbooks:
Introduction to Computing –CS101 VU
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Send an email message to me at altaf@vu.edu.pk with the subject “Assignment 1” giving
me some information (in around 50 words) about what you see yourself doing ten years
from now
Go to the CS101 message board and post a message (consisting of approx. 50 words)
about how we could make the contents of this course more suitable for your individual
needs. The subject for this message should be “Assignment 1”
Consult the CS101 syllabus for the submission deadline
A suggestion about unfamiliar terms
We try not to use any new terms without explaining them first
However, it is not possible to do that all the time
If you encounter any unfamiliar terms during the lectures, please note them down and
consult the GLOSSARY provided at the end of the “Understanding Computers” text
book for their meaning
Let’s summarize the things that we have covered today?
A few things about:
the very first digital computer & its inventor
the capability of modern computers
the structure and contents of CS101
In the Next Lecture …
We’ll continue the story of the evolution of digital computers form the Analytical Engine
onwards.
We’ll discuss many of the key inventions and developments that he lead to the shape of
the current field of computing.
Homew
ork
Assign
ments
15%
Midterm
Examin
ation
35%
Final
Examin
ation
50%
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Lecture 2
Evolution of Computing
Today’s Goal
To learn about the evolution of computing
To recount the important and key events
To identify some of the milestones in computer development
Babbage’s Analytical Engine - 1833
Mechanical, digital, general-purpose
Was crank-driven
Could store instructions
Could perform mathematical calculations
Had the ability to print
Could punched cards as permanent memory
Invented by Joseph-Marie Jacquard
2.1 Turing Machine – 1936
Introduced by Alan Turing in 1936, Turing machines are one of the key abstractions
used in modern computability theory, the study of what computers can and cannot do. A
Turing machine is a particularly simple kind of computer, one whose operations are
limited to reading and writing symbols on a tape, or moving along the tape to the left or
right. The tape is marked off into squares, each of which can be filled with at most one
symbol. At any given point in its operation, the Turing machine can only read or write
on one of these squares, the square located directly below its "read/write" head.
2.2 The “Turing test”
A test proposed to determine if a computer has the ability to think. In 1950, Alan Turing
(Turing, 1950) proposed a method for determining if machines can think. This method is
known as The Turing Test.
The test is conducted with two people and a machine. One person plays the role of an
interrogator and is in a separate room from the machine and the other person. The
interrogator only knows the person and machine as A and B. The interrogator does not
know which the person is and which the machine is.
Using a teletype, the interrogator, can ask A and B any question he/she wishes. The aim
of the interrogator is to determine which the person is and which the machine is.
The aim of the machine is to fool the interrogator into thinking that it is a person. If the
machine succeeds then we can conclude that machines can think.
2.3 Vacuum Tube – 1904:
Interrogator
asking
questions
Human
providing
answers
Computer
on its own
providing
answers
Terminal
Terminal
Computer
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A vacuum tube is just that: a glass tube surrounding a vacuum (an area from which all
gases has been removed). What makes it interesting is that when electrical contacts are
put on the ends, you can get a current to flow though that vacuum.
A British scientist named John A. Fleming made a vacuum tube known today as a diode.
Then the diode was known as a "valve,"
2.4 ABC – 1939
The Atanasoff-Berry Computer was the world's first electronic digital computer. It was
built by John Vincent Atanasoff and Clifford Berry at Iowa State University during 1937-
42. It incorporated several major innovations in computing including the use of binary
arithmetic, regenerative memory, parallel processing, and separation of memory and
computing functions.
2.5 Harvard Mark 1 – 1943:
Howard Aiken and Grace Hopper designed the MARK series of computers at Harvard
University. The MARK series of computers began with the Mark I in 1944. Imagine a
giant roomful of noisy, clicking metal parts, 55 feet long and 8 feet high. The 5-ton
device contained almost 760,000 separate pieces. Used by the US Navy for gunnery and
ballistic calculations, the Mark I was in operation until 1959.
The computer, controlled by pre-punched paper tape, could carry out addition,
subtraction, multiplication, division and reference to previous results. It had special
subroutines for logarithms and trigonometric functions and used 23 decimal place
numbers. Data was stored and counted mechanically using 3000 decimal storage wheels,
1400 rotary dial switches, and 500 miles of wire. Its electromagnetic relays classified the
machine as a relay computer. All output was displayed on an electric typewriter. By
today's standards, the Mark I was slow, requiring 3-5 seconds for a multiplication
operation
2.6 ENIAC – 1946:
ENIAC I (Electrical Numerical Integrator And Calculator). The U.S. military sponsored
their research; they needed a calculating device for writing artillery-firing tables (the
settings used for different weapons under varied conditions for target accuracy).
John Mauchly was the chief consultant and J Presper Eckert was the chief engineer.
Eckert was a graduate student studying at the Moore School when he met John Mauchly
in 1943. It took the team about one year to design the ENIAC and 18 months and
500,000 tax dollars to build it.
The ENIAC contained 17,468 vacuum tubes, along with 70,000 resistors and 10,000
capacitors.
2.7 Transistor – 1947
The first transistor was invented at Bell Laboratories on December 16, 1947 by William
Shockley. This was perhaps the most important electronics event of the 20th century, as
it later made possible the integrated circuit and microprocessor that are the basis of
modern electronics. Prior to the transistor the only alternative to its current regulation
and switching functions (TRANSfer resISTOR) was the vacuum tubes, which could only
be miniaturized to a certain extent, and wasted a lot of energy in the form of heat.
Compared to vacuum tubes, it offered:
smaller size
better reliability
lower power consumption
lower cost
2.8 Floppy Disk – 1950
Invented at the Imperial University in Tokyo by Yoshiro Nakamats
2.9 UNIVAC 1 – 1951
UNIVAC-1. The first commercially successful electronic computer, UNIVAC I, was
also the first general purpose computer - designed to handle both numeric and textual
information. It was designed by J. Presper Eckert and John Mauchly. The
implementation of this machine marked the real beginning of the computer era.
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Remington Rand delivered the first UNIVAC machine to the U.S. Bureau of Census in
1951. This machine used magnetic tape for input.
first successful commercial computer
design was derived from the ENIAC (same developers)
first client = U.S. Bureau of the Census
$1 million
48 systems built
2.10 Compiler - 1952
Grace Murray Hopper an employee of Remington-Rand worked on the NUIVAC. She
took up the concept of reusable software in her 1952 paper entitled "The Education of a
Computer" and developed the first software that could translate symbols of higher
computer languages into machine language. (Compiler)
2.11 ARPANET – 1969
The Advanced Research Projects Agency was formed with an emphasis towards
research, and thus was not oriented only to a military product. The formation of this
agency was part of the U.S. reaction to the then Soviet Union's launch of Sputnik in
1957. (ARPA draft, III-6). ARPA was assigned to research how to utilize their
investment in computers via Command and Control Research (CCR). Dr. J.C.R.
Licklider was chosen to head this effort.
Developed for the US DoD Advanced Research Projects Agency
60,000 computers connected for communication among research organizations and
universities
2.12 Intel 4004 – 1971
The 4004 was the world's first universal microprocessor. In the late 1960s, many
scientists had discussed the possibility of a computer on a chip, but nearly everyone felt
that integrated circuit technology was not yet ready to support such a chip. Intel's Ted
Hoff felt differently; he was the first person to recognize that the new silicon-gated MOS
technology might make a single-chip CPU (central processing unit) possible.
Hoff and the Intel team developed such architecture with just over 2,300 transistors in
an area of only 3 by 4 millimeters. With its 4-bit CPU, command register, decoder,
decoding control, control monitoring of machine commands and interim register, the
4004 was one heck of a little invention. Today's 64-bit microprocessors are still based on
similar designs, and the microprocessor is still the most complex mass-produced product
ever with more than 5.5 million transistors performing hundreds of millions of
calculations each second - numbers that are sure to be outdated fast.
2.13 Altair 8800 – 1975
By 1975 the market for the personal computer was demanding a product that did not
require an electrical engineering background and thus the first mass produced and
marketed personal computer (available both as a kit or assembled) was welcomed with
open arms. Developers Edward Roberts, William Yates and Jim Bybee spent 1973-1974
to develop the MITS (Micro Instruments Telemetry Systems ) Altair 8800. The price was
$375, contained 256 bytes of memory (not 256k),but had no keyboard, no display, and
no auxiliary storage device. Later, Bill Gates and Paul Allen wrote their first product for
the Altair -- a BASIC compiler (named after a planet on a Star Trek episode).
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2.14 Cray 1 – 1 976
It looked like no other computer before, or for that matter, since. The Cray 1 was the
world's first "supercomputer," a machine that leapfrogged existing technology when it
was introduced in 1971.
And back then, you couldn't just order up fast processors from Intel. "There weren't any
microprocessors," says Gwen Bell of The Computer Museum History Center. "These
individual integrated circuits that are on the board performed different functions."
Each Cray 1, like this one at The Computer Museum History Center, took months to
build. The hundreds of boards and thousands of wires had to fit just right. "It was really
a hand-crafted machine," adds Bell. "You think of all these wires as a kind of mess, but
each one has a precise length."
2.15 IBM PC – 1981
On August 12, 1981, IBM released their new computer, re-named the IBM PC. The
"PC" stood for "personal computer" making IBM responsible for popularizing the term
"PC".
The first IBM PC ran on a 4.77 MHz Intel 8088 microprocessor. The PC came equipped
with 16 kilobytes of memory, expandable to 256k. The PC came with one or two 160k
Floppy Disks Drives and an optional color monitor. The price tag started at $1,565,
which would be nearly $4,000 today.
2.16 Apple Macintosh – 1984
Apple introduced the Macintosh to the nation on January 22, 1984. The original
Macintosh had 128 kilobytes of RAM, although this first model was simply called
"Macintosh" until the 512K model came out in September 1984. The Macintosh retailed
for $2495. It wasn't until the Macintosh that the general population really became aware
of the mouse-driven graphical user interface.
2.17 World Wide Web -1989
"CERN is a meeting place for physicists from all over the world, who collaborate on
complex physics, engineering and information handling projects. Thus, the need for the
WWW system arose "from the geographical dispersion of large collaborations, and the
fast turnover of fellows, students, and visiting scientists," who had to get "up to speed
on projects and leave a lasting contribution before leaving."
CERN possessed both the financial and computing resources necessary to start the
project. In the original proposal, Berners-Lee outlined two phases of the project:
First, CERN would "make use of existing software and hardware as well as
implementing simple browsers for the user's workstations, based on an analysis of the
requirements for information access needs by experiments."
Second, they would "extend the application area by also allowing the users to add new
material."
Berners-Lee expected each phase to take three months "with the full manpower
complement": he was asking for four software engineers and a programmer. The
proposal talked about "a simple scheme to incorporate several different servers of
machine-stored information already available at CERN."
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Set off in 1989, the WWW quickly gained great popularity among Internet users. For
instance, at 11:22 am of April 12, 1995, the WWW server at the SEAS of the University
of Pennsylvania "responded to 128 requests in one minute. Between 10:00 and 11:00
2.18 Quantum Computing with Molecules
by Neil Gershenfeld and Isaac L. Chuang
Factoring a number with 400 digits--a numerical feat needed to break some security
codes--would take even the fastest supercomputer in existence billions of years. But a
newly conceived type of computer, one that exploits quantum-mechanical interactions,
might complete the task in a year or so, thereby defeating many of the most
sophisticated encryption schemes in use. Sensitive data are safe for the time being,
because no one has been able to build a practical quantum computer. But researchers
have now demonstrated the feasibility of this approach. Such a computer would look
nothing like the machine that sits on your desk; surprisingly, it might resemble the cup of
coffee at its side.
Several research groups believe quantum computers based on the molecules in a liquid
might one day overcome many of the limits facing conventional computers. Roadblocks
to improving conventional computers will ultimately arise from the fundamental physical
bounds to miniaturization (for example, because transistors and electrical wiring cannot
be made slimmer than the width of an atom). Or they may come about for practical
reasons--most likely because the facilities for fabricating still more powerful microchips
will become prohibitively expensive. Yet the magic of quantum mechanics might solve
both these problems.
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Lecture 3
Today’s Goal is to …
Become familiar with the World Wide Web
Become familiar with the Web’s structure and how the Web works
Learn about its genesis, its evolution, and its future
About its impact on computing, society, commerce
3.1 Browser
A browser is an application program that provides a way to look at and interact with all
the information on the World Wide Web. The word "browser" seems to have originated
prior to the Web as a generic term for user interfaces that let you browse (navigate
through and read) text files online. By the time the first Web browser with a graphical
user interface was generally available (Mosaic, in 1993), the term seemed to apply to Web
content, too. Technically, a Web browser is a client program that uses the Hypertext
Transfer Protocol (HTTP) to make requests of Web servers throughout the Internet on
behalf of the browser user.
3.2 URL
URL (Uniform Resource Locator, previously Universal Resource Locator) - pronounced
YU-AHR-EHL or, in some quarters, UHRL - is the address of a file (resource)
accessible on the Internet. The type of file or resource depends on the Internet
application protocol. Using the World Wide Web's protocol, the Hypertext Transfer
Protocol (HTTP), the resource can be an HTML page (like the one you're reading), an
image file, or any other file supported by HTTP. The URL contains the name of the
protocol required to access the resource, a domain name that identifies a specific
computer on the Internet, and a pathname (hierarchical description of a file location) on
the computer.
On the Web (which uses the Hypertext Transfer Protocol), an example of a URL is:
http://www.ietf.org/rfc/rfc2396.txt
Which describes a Web page to be accessed with an HTTP (Web browser) application
that is located on a computer named www.ietf.org. The pathname for the specific file in
that computer is /rfc/rfc2396.txt.
An HTTP URL can be for any Web page, not just a home page, or any individual file.
Examples:
http://dawn.com
http://www.vu.edu.pk
http://www.smeda.org.pk
3.3 What is a Web site?
A Web site is a related collection of World Wide Web (WWW) files that includes a
beginning file called a home page. A company or an individual tells you how to get to
their Web site by giving you the address of their home page. From the home page, you
can get to all the other pages on their site. For example, the Web site for IBM has the
home page address of http://www.ibm.com. IBM's home page address leads to
thousands of pages but a web site can also be just of few pages.
http://www.vu.edu.pk/
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3.4 What is Home Page of a web site?
1) For a Web user, the home page is the first Web page that is displayed after starting a
Web browser like Netscape's Navigator or Microsoft's Internet Explorer. The browser is
usually preset so that the home page is the first page of the browser manufacturer.
However, you can set it to open to any Web site. For example, you can specify that
"http://www.yahoo.com" or "http://whatis.com" be your home page. You can also
specify that there be no home page (a blank space will be displayed) in which case you
choose the first page from your bookmark list or enter a Web address.
2) For a Web site developer, a home page is the first page presented when a user selects
a site or presence on the World Wide Web. The usual address for a Web site is the home
page address, although you can enter the address (Uniform Resource Locator) of any
page and have that page sent to you.
3.5 Who invented the Web & Why?
"CERN is a meeting place for physicists from all over the world, who collaborate on
complex physics, engineering and information handling projects. Thus, the need for the
WWW system arose "from the geographical dispersion of large collaborations, and the
fast turnover of fellows, students, and visiting scientists," who had to get "up to speed
on projects and leave a lasting contribution before leaving."
CERN possessed both the financial and computing resources necessary to start the
project. In the original proposal, Berners-Lee outlined two phases of the project:
First, CERN would "make use of existing software and hardware as well as
implementing simple browsers for the user's workstations, based on an analysis of the
requirements for information access needs by experiments."
Second, they would "extend the application area by also allowing the users to add new
material."
Berners-Lee expected each phase to take three months "with the full manpower
complement": he was asking for four software engineers and a programmer. The
proposal talked about "a simple scheme to incorporate several different servers of
machine-stored information already available at CERN."
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Set off in 1989, the WWW quickly gained great popularity among Internet users. For
instance, at 11:22 am of April 12, 1995, the WWW server at the SEAS of the University
of Pennsylvania "responded to 128 requests in one minute. Between 10:00 and 11:00
3.6 Future of the Web: Semantic Web
The Semantic Web is an idea of World Wide Web inventor Tim Berners-Lee that the
Web as a whole can be made more intelligent and perhaps even intuitive about how to
serve a user's needs. Berners-Lee observes that although search engines index much of
the Web's content, they have little ability to select the pages that a user really wants or
needs. He foresees a number of ways in which developers and authors, singly or in
collaborations, can use self-descriptions and other techniques so that contextunderstanding
programs can selectively find what users want.
3.7 Useful Web page
Web page for our “Understanding Computers” text book
http://www.hbcollege.com/infosys/parker2000
What have we learnt today?
What is the World Wide Web?
How does it work?
About its expected evolution into the Semantic Web
The impact of the Web on computing, society, and commerce
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Lecture 4
Today’s Goal
To learn to classify computers according to their capability and targeted applications
To find out about the essential building blocks that make up a modern computer
Computer Types According to Capability
4.1 Computer Types According to Capability
4.2 Supercomputers
A supercomputer is a computer that performs at or near the currently highest
operational rate for computers. A supercomputer is typically used for scientific and
engineering applications that must handle very large databases or do a great amount of
computation (or both). At any given time, there are usually a few well-publicized
supercomputers that operate at the very latest and always incredible speeds.
Perhaps the best-known builder of supercomputers has been Cray Research, now a part
of Silicon Graphics. Some supercomputers are at "supercomputer center," usually
university research centers, some of which, in the United States, are interconnected on
an Internet backbone (A backbone is a larger transmission line that carries data gathered
from smaller lines that interconnect with it) known as vBNS or NSFNet.
At the high end of supercomputing are computers like IBM's "Blue Pacific," announced
on October 29, 1998. Built in partnership with Lawrence Livermore National Laboratory
operations per second), 15,000 times faster than the average personal computer. It
consists of 5,800 processors containing a total of 2.6 trillion bytes of memory and
interconnected with five miles of cable.
4.3 Mainframe Computers
A very large and expensive computer capable of supporting hundreds, or even
thousands, of users simultaneously. In the hierarchy that starts with a simple
microprocessor (in watches, for example) at the bottom and moves to supercomputers at
the top, mainframes are just below supercomputers. In some ways, mainframes are more
powerful than supercomputers because they support more simultaneous programs. But
supercomputers can execute a single program faster than a mainframe. The distinction
between small mainframes and minicomputers is vague (not clearly expressed),
depending really on how the manufacturer wants to market its machines.
4.4 Servers / Minicomputers
A midsized computer. In size and power, minicomputers lie between workstations and
mainframes. In the past decade, the distinction between large minicomputers and small
mainframes has blurred, however, as has the distinction between small minicomputers
and workstations. But in general, a minicomputer is a multiprocessing system capable of
supporting from 4 to about 200 users simultaneously.
4.5 Desktops
These are also called microcomputers. Low-end desktops are called PC’s and high-end
ones “Workstations”. These are generally consisting of a single processor only, some
times 2, along with MB’s of memory, and GB’s of storage. PC’s are used for running
productivity applications, Web surfing, messaging. Workstations are used for more
demanding tasks like low-end 3-D simulations and other engineering & scientific apps.
These are not as reliable and fault-tolerant as servers. Workstations cost a few thousand
dollars; PC around a $1000.
4.6 Portables
Portable computer is a personal computer that is designed to be easily transported and
relocated, but is larger and less convenient to transport than a notebook computer. The
earliest PCs designed for easy transport were called portables. As the size and weight of
most portables decreased, they became known as laptop computer and later as notebook
computer. Today, larger transportable computers continue to be called portable computers.
Most of these are special-purpose computers - for example, those for use in industrial
environments where they need to be moved about frequently.
in California, Blue Pacific is reported to operate at 3.9 teraflop (trillion floating point
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PDA (personal digital assistant) is a term for any small mobile hand-held device that
provides computing and information storage and retrieval capabilities for personal or
business use, often for keeping schedule calendars and address book information handy.
The term handheld is a synonym. Many people use the name of one of the popular PDA
products as a generic term. These include Hewlett-Packard's Palmtop and 3Com's
PalmPilot.
Most PDAs have a small keyboard. Some PDAs have an electronically sensitive pad on
which handwriting can be received. Apple's Newton, which has been withdrawn from
the market, was the first widely-sold PDA that accepted handwriting. Typical uses
include schedule and address book storage and retrieval and note-entering. However,
many applications have been written for PDAs. Increasingly, PDAs are combined with
telephones and paging systems.
Some PDAs offer a variation of the Microsoft Windows operating system called
Windows CE. Other products have their own or another operating system.
4.7 Ranking w.r.t. installed number
PC’s
PDA’s
Workstations
Servers
Wearable (picture is provided)
Mainframes
Supercomputers
At the highest level, two things are required for computing
Hardware
Computer equipment such as a CPU, disk drives, CRT, or printer
Software
A computer program, which provides the instructions which enable the computer
hardware to work
4.8 All computers have the following essential hardware components:
Input
The devices used to give the computer data or commands are called Input devices.
Includes keyboard, mouse, scanner, etc
Processor
A processor is the logic circuitry that responds to and processes the basic instructions
that drive a computer.
The term processor has generally replaced the term central processing unit (CPU). The
processor in a personal computer or embedded in small devices is often called a
microprocessor.
Short for microprocessor, the central processing unit in a computer. The processor is the
logic of a computer and functions comparably to a human central nervous system,
directing signals from one component to another and enabling everything to happen
Memory
Memory is the electronic holding place for instructions and data that your computer's
microprocessor can reach quickly. When your computer is in normal operation, its
memory usually contains the main parts of the operating system and some or all of the
application programs and related data that are being used. Memory is often used as a
shorter synonym for random access memory (RAM). This kind of memory is located on
one or more microchips that are physically close to the microprocessor in your
computer. Most desktop and notebook computers sold today include at least 16
megabytes of RAM, and are upgradeable to include more. The more RAM you have, the
less frequently the computer has to access instructions and data from the more slowly
accessed hard disk form of storage.
Memory is also called primary or main memory.
Storage
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Computer storage is the holding of data in an electromagnetic form for access by a
computer processor. It is also called secondary storage. In secondary storage data resides
on hard disks, tapes, and other external devices.
Primary storage is much faster to access than secondary storage because of the proximity
of the storage to the processor or because of the nature of the storage devices. On the
other hand, secondary storage can hold much more data than primary storage.
Output
The devices to which the computer writes data are called Output devices. Often converts
the data into a human readable form. Monitor and printer are output devices.
4.9 Input Devices
Mouse
A mouse is a small device that a computer user pushes across a desk surface in order to
point to a place on a display screen and to select one or more actions to take from that
position. The mouse first became a widely-used computer tool when Apple Computer
made it a standard part of the Apple Macintosh. Today, the mouse is an integral part of
the graphical user interface (GUI) of any personal computer. The mouse apparently got
its name by being about the same size and color as a toy mouse.
Keyboard
On most computers, a keyboard is the primary text input device. A keyboard on a
computer is almost identical to a keyboard on a typewriter. Computer keyboards will
typically have extra keys, however. Some of these keys (common examples include
Control, Alt, and Meta) are meant to be used in conjunction with other keys just like
shift on a regular typewriter. Other keys (common examples include Insert, Delete,
Home, End, Help, function keys, etc.) are meant to be used independently and often
perform editing tasks.
Joystick
In computers, a joystick is a cursor control device used in computer games. The joystick,
which got its name from the control stick used by a pilot to control the ailerons and
elevators of an airplane, is a hand-held lever that pivots on one end and transmits its
coordinates to a computer. It often has one or more push-buttons, called switches,
whose position can also be read by the computer.
Digital Camera
A digital camera records and stores photographic images in digital form that can be fed
to a computer as the impressions are recorded or stored in the camera for later loading
into a computer or printer. Currently, Kodak, Canon, and several other companies make
digital cameras.
Microphone
A device that converts sound waves into audio signals. These could be used for sound
recording as well as voice chatting through internet.
Scanner
A scanner is a device that captures images from photographic prints, posters, magazine
pages, and similar sources for computer editing and display. Scanners come in hand-held,
feed-in, and flatbed types and for scanning black-and-white only, or color. Very high
resolution scanners are used for scanning for high-resolution printing, but lower
Keyboard Mouse
Memory Printer
Hard
Disk
Memory
Bus
System Bus
Monitor
Compact
Disk
Processor
Integer
Unit
Control
Unit
Cache
Memory
Floating
Point
Unit
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resolution scanners are adequate for capturing images for computer display. Scanners
usually come with software, such as Adobe's Photoshop product, that lets you resize and
otherwise modify a captured image
4.10 What is Port?
On computer and telecommunication devices, a port (noun) is generally a specific place
for being physically connected to some other device, usually with a socket and plug of
some kind. Typically, a personal computer is provided with one or more serial ports and
usually one parallel port.
4.11Many Types of Ports
Parallel
An interface on a computer that supports transmission of multiple bits at the same time;
almost exclusively used for connecting a printer. On IBM or compatible computers, the
parallel port uses a 25-pin connector.
Serial
It is a general-purpose personal computer communications port in which 1 bit of
information is transferred at a time. In the past, most digital cameras were connected to
a computer's serial port in order to transfer images to the computer. Recently, however,
the serial port is being replaced by the much faster USB port on digital cameras as well as
computers.
SCSI
A port that's faster than the serial and parallel ports but slower and harder to configure
than the newer USB port. Also know as the Small Computer System Interface.
A high-speed connection that enables devices, such as hard-disk drives and network
adapters, to be attached to a computer.
USB
USB (Universal Serial Bus) is a plug-and-play hardware interface for peripherals such as
the keyboard, mouse, joystick, scanner, printer and modem. USB has a maximum
bandwidth of 12 Mbits/sec and up to 127 devices can be attached. With USB, a new
device can be added to your computer without having to add an adapter card. It typically
is located at the back of the PC
Firewire
FireWire is simply a really fast port that lets you connect computer peripherals and
consumer electronics to your computer without the need to restart. It is a simple
common plug-in serial connector on the back of your computer.
It has the ability to chain devices together in a number of different ways without
terminators for example, simply join 2 computers with a FireWire cable for instant highspeed
networking.
4.12 Processor
Pentium
Celeron
Athlon
PowerPC
StrongARM (PDA)
Crusoe (Laptops)
SPARC (Workstations)
4.13 Memory/Storage
RAM
RAM (random access memory) is the place in a computer where the operating system,
application programs, and data in current use are kept so that they can be quickly
reached by the computer's processor. RAM is much faster to read from and write to than
the other kinds of storage in a computer, the hard disk, floppy disk, and CD-ROM.
However, the data in RAM stays there only as long as your computer is running. When
you turn the computer off, RAM loses its data. When you turn your computer on again,
your operating system and other files are once again loaded into RAM, usually from your
hard disk.
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Punch cards
A card on which data can be recorded in the form of punched holes.
ROM
ROM is "built-in" computer memory containing data that normally can only be read, not
written to. ROM contains the programming that allows your computer to be "booted
up" or regenerated each time you turn it on. Unlike a computer's random access memory
(RAM), the data in ROM is not lost when the computer power is turned off.
The ROM is sustained by a small long-life battery in your computer.
Hard disk
Hard disk is a computer storage device which saves and retrieves the data when
required. Its capacity is much greater than the computer memory (RAM, ROM). Data on
hard disk is stored and retrieved from electromagnetically charged surface.
Today we can save huge amount of data on a single hard disk. Now hard disks can
contain several billion bytes.
Floppy disk
A diskette is a random access, removable data storage medium that can be used with
personal computers. The term usually refers to the magnetic medium housed in a rigid
plastic cartridge measuring 3.5 inches square and about 2 millimeters thick. Also called a
"3.5-inch diskette," it can store up to 1.44 megabytes (MB) of data.
Tape
In computers, tape is an external storage medium, usually both readable and writable,
can store data in the form of electromagnetic charges that can be read and also erased. A
tape drive is the device that positions, writes from, and reads to the tape.
CD
A compact disc [sometimes spelled disk] (CD) is a small, portable, round medium for
electronically recording, storing, and playing back audio, video, text, and other
information in digital form.
DVD
DVD (digital versatile disc) is an optical disc technology that is expected to rapidly
replace the CD-ROM disc (as well as the audio compact disc) over the next few years.
The digital versatile disc (DVD) holds 4.7 gigabyte of information on one of its two
sides, or enough for a 133-minute movie.
4.14 Classifying Memory/Storage
Electronic (RAM, ROM), magnetic (HD, FD, Tape), optical (CD, DVD)
Volatile (RAM), non-volatile (HD)
Direct access (RAM, HD), serial access (Tape)
Read/write (HD, RAM), read-only (CD)
4.15 Output Devices
Printer
Plotter
Speakers
Monitor
4.16 Modem
Modem is output as well as input device at the same time. It receives the data (analog
signal) coming through telephone line, converts them to digital signals and sends them to
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computer to which it is attached. It also receives the data from computer and changes it
to analog signals.
What have we learnt today?
What are the various types of computers with respect to their size, capability,
applications (FIVE TYPES)
The five essential components of any computer are input devices, processor, memory,
storage and output devices
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Lecture 5
Today’s goal is quite simple …
To learn about the various components of the popular personnel computer.
How those things are put together to form a PC
5.1 PC Parts
Monitor
Keyboard
Mouse
Speaker/headphone
Microphone
CPU
Front buttons
Backside ports, fan, slots, cables
5.2 Inside of the CPU
Power supply/fan & connectors
Motherboard
Bus
Edge connectors
Ports
Video card
Modem
Network card
Sound card
ROM
RAM
Slots
DIMM’s
5.3 The Processor Module
The slot on the motherboard
The housing
Fan
Heat sink
Pins (256?), Transistors (10 million?)
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Lecture 6
Learning Goals for Today
6.1 To develop your personal Web page
To upload your Web page to VU’s Web server so that it becomes visible on the Internet
as http://www.vu.edu.pk/~xxxxxxx/
where xxxxxxx is your user ID
http://www.vu.edu.pk/~altaf
HTML
Hyper Text Markup Language
<HTML>
<HEAD>
<TITLE>Altaf Khan's Home Page</TITLE>
</HEAD>
<BODY>
<H1>Altaf Khan</H1>
<P><B>Adjunct Lecturer in Computer Science</B><BR>
<A HREF="http://www.vu.edu.pk/">Virtual University</A><BR>
Building 1, 3rd Floor, Aiwan-e-Iqbal, Lahore<BR>
+92 42 555 1212<BR>
<A HREF="mailto:altaf@vu.edu.pk">altaf@vu.edu.pk</A><BR></P>
<P>I teach the <A HREF="http://www.vu.edu.pk/cs101/">Introduction to
Computing</A> course. </P>
</BODY>
</HTML>
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
29
http://www.vu.edu.pk/~altaf/index.html
http://www.vu.edu.pk/~altaf
http://www.vu.edu.pk/~xxxxxxx
where xxxxxxx is your user ID
<HTML>
…
…
</HTML>
<HEAD>
…
…
</HEAD>
<TITLE> … </TITLE>
<BODY>
…
…
</BODY>
<P> … </P>
Paragraph
<BR>
Line break
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
30
<B> … </B>
Bold text
<A HREF = “action” > label </A>
http://
example: “http://www.vu.edu.pk”
mailto:
example: “mailto:altaf@vu.edu.pk”
HTML Code
I am at the
<A HREF=“http://www.vu.edu.pk”>Virtual University</A>. You can send me an
e-mail by clicking
<A HREF=“mailto:bhola@vu.edu.pk”>here</A>.
Browser Display
I am at the Virtual University. You can send me an e-mail by clicking here.
What have we learned today?
We now know how Web pages are built using HTML
We also know how to make our personal Web pages available to everyone on the Internet
Useful URL’s
HTML for the Conceptually Challenged
http://www.arachnoid.com/lutusp/html_tutor.html
NCSA’s Beginner's Guide to HTML
http://archive.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimerAll.html
Homework Assignment
Develop your own home page. It should be accessible as
http://www.vu.edu.pk/~xxxxxxx (xxxxxxxx is your user ID)
Among other things, it should contain
At least one link to http://www.vu.edu.pk/~altaf
Your (clickable) email address
A paragraph (50-100 words) on what you see yourself doing 10 years from now.
Consult your syllabus for the submission deadline for this assignment
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
31
Lecture 7
Goals for Today
Today we want to learn about the microprocessor, the key component, the brain, of a
computer
We’ll learn about the function of a microprocessor
And its various sub-systems
Bus interface unit
Data & instruction cache memory
Instruction decoder
Arithmetic-Logic unit
Floating-point unit
Control unit
7.1 Microprocessor
A microprocessor (abbreviated as μP or uP) is a computer processor on a microchip. It's
sometimes called a logic chip. A microprocessor is designed to perform arithmetic and
logic operations that make use of small number-holding areas called registers. Typical
microprocessor operations include adding, subtracting, comparing two numbers, and
fetching numbers from one area to another. These operations are the result of a set of
instructions that are part of the microprocessor design. When the computer is turned on,
the microprocessor is designed to get the first instruction from the basic input/output
system (BIOS) that comes with the computer as part of its memory. After that, either the
BIOS, or the operating system that BIOS loads into computer memory, or an
application program is "driving" the microprocessor, giving it instructions to perform.
The number of transistors available has a huge effect on the performance of a processor.
As seen earlier, a typical instruction in a processor like an 8088 took 15 clock cycles to
execute. Because of the design of the multiplier, it took approximately 80 cycles just to
do one 16-bit multiplication on the 8088. With more transistors, much more powerful
multipliers capable of single-cycle speeds become possible.
A microprocessor is made from miniaturized transistors and other circuit elements on a
silicon.
7.2 Integrated Circuits
A chip is also called an (integrated circuit (IC) (aka microchip or just chip). It is a
microelectronic semiconductor device consisting of many interconnected transistors and
other components.Generally it is a small, thin piece of silicon onto which the transistors
making up the microprocessor have been etched.
A chip might be as large as an inch on a side and can contain tens of millions of
transistors. Simpler processors might consist of a few thousand transistors etched onto a
chip just a few millimeters square. Integrated circuits can be classified into analog, digital
and mixed signal (both analog and digital on the same chip). Digital integrated circuits
can contain anything from one to millions of logic gates, flip-flops, multiplexers, etc. in a
few square millimeters. The small size of these circuits allows high speed, low power
dissipation, and reduced manufacturing cost compared with board-level integration.
The growth of complexity of integrated circuits follows a trend called "Moore's Law", it
states that the number of transistors in an integrated circuit doubles every two years.
7.3 Devices
7.3.1 Transistors
single semiconductor integrated circuit (IC) . These are made up of semiconductor and
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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The transistor is a solid state semiconductor device used for amplification and
switching, and has three terminals. A small current or voltage applied to one terminal
controls the current through the other two, hence the term transistor; a voltage- or
current-controlled resistor. It is the key component in all modern electronics. In digital
circuits, transistors are used as very fast electrical switches, and arrangements of
transistors can function as logic gates, RAM-type memory and other devices. In analog
circuits, transistors are essentially used as amplifiers.
7.3.2 Diodes
A diode functions as the electronic version of a one-way valve. By restricting the
direction of movement of charge carriers, it allows an electric current to flow in one
direction, but blocks it in the opposite direction.
A diode's current-voltage, or I-V, characteristic can be approximated by two regions of
operation. Below a certain difference in potential between the two leads, the diode can
be thought of as an open (non-conductive) circuit. As the potential difference is
increased, at some stage the diode will become conductive and allow current to flow, at
which point it can be thought of as a connection with zero (or at least very low)
resistance. In a typical semiconductor p-n diode, conventional current can flow from the
p-doped side to the n-doped side, but not in the opposite direction. When the diode is
reverse-biased, the charge carriers are pulled away from the center of the device, creating
a depletion region. More specifically, the transfer function is logarithmic, but so sharp
that it looks like a corner.
7.3.3 Resistors
A resistor is an electrical component designed to have an electrical resistance that is
independent of the current flowing through it. The common type of resistor is also
designed to be independent of temperature and other factors. Resistors may be fixed or
variable. Variable resistors are also called potentiometers or rheostats
A few resistor types
Some resistors are long and thin, with the actual resisting material in the centre, and a
conducting metal leg on each end. This is called an axial package.
Resistors used in computers and other devices are typically much smaller, often in surfacemount
(Surface-mount technology) packages without leads.
Larger power resistors come in more sturdy packages designed to dissipate heat
efficiently, but they are all basically the same structure. Resistors are used as part of
electrical networks and incorporated into microelectronic semiconductor devices. The
critical measurement of a resistor is its resistance, which serves as a ratio of voltage to
current and is measured in ohms, an SI unit. Any physical object is a kind of resistor.
Most metals are conductors, and have low resistance to the flow of electricity. The
human body, a piece of plastic, or even a vacuum has a resistance that can be measured.
Materials that have very high resistance are called insulators.
7.3.4 Capacitors
A capacitor (historically known as a "condenser") is a device that stores energy in an
electric field, by accumulating an internal imbalance of electric charge. An ideal capacitor
can store electronic energy when disconnected from its charging circuit, so it can be used
like a fast battery. In AC or signal circuits it induces a phase difference of 90 degrees,
current leading potential.
They are connected in parallel with the power circuits of most electronic devices and
larger systems (such as factories) to shunt away and conceal current fluctuations from
the primary power source to provide a "clean" power supply for signal or control
circuits. The effect of such capacitors can be thought of in two different ways. One way
of thinking about it is that the capacitors act as a local reserve for the DC power source,
to smooth out fluctuations by charging and discharging each cycle. The other way to
think about it is that the capacitor and resistance of the power supply circuitry acts as a
filter and removes high frequencies, leaving only DC.
Wires
And are made of the following materials
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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Silicon - semiconductor
Copper - conductor
Silicon Dioxide - insulator
7.4 Microprocessor system
Microprocessors are powerful pieces of hardware, but not much useful on their own.
They do not have the sense of their own. Like the human sample it needs some
instructions inputs and outputs to process some task. As per instruction given to the
microprocessor.
A microprocessor system is microprocessor plus all the components it requires to do a
certain task.
Shortly, a microprocessor needs help of some components to make up the task to fulfill.
These components are input, output, storage, and memory. All these components and
microprocessor make up a microprocessor system.
Personal Computer is an example of microprocessor System. Another example is the
microcontroller.
7.5 Micro-controllers
A microcontroller is a microprocessor optimised to be used to control electronic
equipment. Microcontrollers represent the vast majority of all computer chips sold, over
50% are "simple" controllers, and another 20% are more specialized decipline
processors. While you may have one or two general-purpose microprocessors in your
house (you're using one to read this), you likely have somewhere between one and two
dozen microcontrollers. They can be found in almost any electrical device, washing
machines, microwave ovens, telephones etc.
A microcontroller includes CPU, memory for the program (ROM), memory for data
(RAM), I/O lines to communicate with peripherals and complementary resources, all
this in a closed chip. A microcontroller differs from a standalone CPU, because the first
one generally is quite easy to make into a working computer, with a minimum of external
support chips. The idea is that the microcontroller will be placed in the device to control,
hooked up to power and any information it needs, and that's that.
7.6 The Main Memory Bottleneck
Modern super-fast microprocessors can process a huge amount of data in a short
duration. They need data to be processed at the same speed. Other wise they have to sit
idle and wait for the input/data, because speed of input is rather small then processing
of data. They require quick access to data to maximize their performance. If they don’t
receive the data that they require, they literally stop and wait, this results in reduced
performance and wasted power.
Current microprocessors can process an instruction in about ns (nanosecond). Time
required for fetching data from main memory (RAM) is of the order of 100 ns
Solution to the Bottleneck Problem
In order to eliminate the solution it was suggested to make the main memory faster. But
that evolved a problem that the 1-ns memory is extremely expensive as compared the
currently popular 100-ns memory.
Finally it was decided that in addition to the relatively slow main memory, put a small
amount of ultra-fast RAM right next to the microprocessor on the same chip and make
sure that frequently used data and instructions resides in that ultra-fast memory
It increases the performance. It supports better over performance due to fast access to
frequently used data and instructions.
7.7 Cache
A cache is a collection of duplicate data, where the original data is expensive to fetch or
compute (usually in terms of access time) relative to the cache. Future accesses to the
data can be made by accessing the cached copy rather than refetching or recomputing
the original data, so that the perceived average access time is lower. Caches may mark the
cached data as 'stale' when the original data is changed, but this is not always the case.
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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On-Chip Cache Memory (1)
That small amount of memory located on the same chip as the microprocessor is called
On-Chip Cache Memory.
The microprocessor stores a copy of frequently used data and instructions in its cache
memory. When the microprocessor desires to look at a piece of data, it checks in the
cache first. If it is not there, only then the microprocessor asks for the same from the
main memory
On-Chip Cache Memory (2)
L2, cache memory, which is on a separate chip from the microprocessor but faster to
access than regular RAM.
It is the small size and proximity to the microprocessor makes access times short,
resulting in a boost in performance. Microprocessors predict what data will be required
for future calculations and it pre-fetches that data and places it in the cache so that it is
available immediately when the need arises.
7.8 Microprocessors Building Blocks
Bus Interface Unit
The bus interface unit is the part of the processor that interfaces with the rest of the PC.
Its name comes from the fact that it deals with moving information over the processor
data bus, the primary conduit for the transfer of information to and from the CPU. The
bus interface unit is responsible for responding to all signals that go to the processor,
and generating all signals that go from the processor to other parts of the system.
It receives instructions & data from main memory to be processed and operations. After
the operations are processed it then sends back the information (processed data) to the
cache. It also receives the processed data to send it to the main memory.
Instruction Decoder
The instruction decoder of a processor is a combinatorial circuit sometimes in the form of a
read-only memory, sometimes in the form of an ordinary combinatorial circuit. Its
purpose is to translate an instruction code into the address in the micro memory where
the micro code for the instruction starts.
Registers
Registers
Microprocessor
Instruction
Cache
Arithmetic
& Logic
Unit
Control
Bus Unit
Interface
Unit
Data
Cache
Instruction
Decoder
I/O
RAM
Memory
Bus
System
Bus
Floating
Point
Unit
Introduction to Computing –CS101 VU
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A decoder is a device which is the reverse, undoing the encoding so that the original
information can be retrieved. The same method used to encode is usually just reversed in
order to decode.This unit receives the programming instructions and decodes them into
a form that is understandable by the processing units, i.e. The ALU or FPU Then, it
passes on the decoded instruction to the ALU or FPUs as desired.
Arithmetic & Logic Unit (ALU)
An arithmetic and logical unit (ALU) also known as “Integer Unit” is one of the core
components of all central processing units. It is capable of calculating the results of a
wide variety of common computations. The most common available operations are the
integer arithmetic operations of addition, subtraction, and multiplication, the bitwise
logic operations of AND, NOT, OR, and XOR, and various shift operations.
The ALU takes as inputs the data to be operated on and a code from the control unit
indicating which operation to perform, and for output provides the result of the
computation. In some designs it may also take as input and output a set of condition
codes, which can be used to indicate cases such as carry-in or carry-out, overflow, or
other statuses.
The new breed of popular microprocessors have not one but two almost identical ALU’s
that can do calculations simultaneously, doubling the capability
Floating-Point Unit (FPU)
A floating point unit (FPU) is a part of a CPU specially designed to carry out
operations on floating point numbers. Typical operations are floating point arithmetic
(such as addition and multiplication), but some systems may be capable of performing
exponential or trigonometric calculations as well (such as square roots or cosines).
Not all CPUs have a dedicated FPU. In the absence of an FPU, the CPU may use a
microcode program to emulate an FPUs function using an arithmetic and logical unit
(ALU), which saves the added hardware cost of an FPU but is significantly slower.
In some computer architectures, floating point operations are handled completely
separate from integer operations, with dedicated floating point registers and independent
clocking schemes. Floating point addition and multiplication operations are typically
pipelined, but more complicated operations, like division, may not be, and some systems
may even have a dedicated floating point divider circuit.
Registers
A register is a device for storing data. It is a small amount of very fast computer
memory used to speed the execution of computer programs by providing quick access to
commonly used values. These registers are the top of the memory hierarchy, and are the
fastest way for the system to manipulate data. It is common to measure registers by the
number of bits it can hold, for example, an "8-bit register" or "32-bit register". Registers
are now usually implemented as an array of SRAMs, but they have also been
implemented using individual flip flops, high speed core memory, thin film memory, and
other ways in various machines.
There are several other classes of registers:
Data registers are used to store integer numbers.
Address registers hold memory addresses and are used to access memory.
General Purpose registers can store both data and addresses.
Floating Point registers are used to store floating point numbers.
Constant registers hold read-only values (e.g zero or one).
Vector registers hold data for Single Instruction Multiple Data (SIMD) instructions.
Special Purpose registers which store internal CPU data like the stack pointer or
processor status words.
The ALU & FPU store intermediate and final results from their calculations in these
registers. Then the processed data goes back to the data cache and then to main memory
from these registers.
Control Unit
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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A control unit is the part of a CPU or other device that directs its operation. The
outputs of the unit control the activity of the rest of the device. A control unit can be
thought of as a finite state machine. It is called the brain of computer microprcessor. It
manages whole process of the microprocessor. For it identifes which data is sent to the
ALU or memory etc.
At one time control units for CPUs were ad-hoc logic, and they were difficult to design.
Now they are often implemented as a microprogram that is stored in a control store.
That was the structure, now let’s talk about the language of a microprocessor
Instruction Set
The set of machine instructions that a microprocessor recognizes and can execute – the
only language microprocessor knows
An instruction set includes low-level, a single step-at-a-time instructions, such as add,
subtract, multiply, and divide
Each microprocessor family has its unique instruction set
Bigger instruction-sets mean more complex chips (higher costs, reduced efficiency), but
shorter programs
An instruction set, or instruction set architecture (ISA), is a specification detailing the
commands that a computer's CPU should be able to understand and execute, or the set
of all commands implemented by a particular CPU design. The term describes the
aspects of a computer or microprocessor typically visible to a programmer, including the
native datatypes, instructions, registers, memory architecture, interrupt and fault system,
and external I/O (if any). "Instruction set architecture" is sometimes used to distinguish
this set of characteristics from the Micro-Architecture, which are the elements and
techniques used to implement the ISA, e.g. microcode, pipelining, cache systems, etc.
Bigger instruction-sets mean more complex chips (higher costs, reduced efficiency), but
shorter programs. Each microprocessor family has its unique instruction set. Following
are the few ISA;
MIPS
Motorola 6800
ARM
PowerPC
x86 (Pentium)
ALGOL Object Code
SPARC
7.9The 1st microprocessor : Intel 4004
The first microprocessor was the Intel 4004, introduced in 1971. The 4004 was not very
powerful all it could do was add and subtract, and it could only do that 4 bits at a time. But it
was amazing that everything was on one chip. Prior to the 4004, engineers built computers
Registers
Registers
Arithmetic
& Logic
Unit
Control
Bus Unit
Interface
Unit
Data
Cache
Instruction
Decoder
I/O
Memory
Bus
System
Bus Floating
Point
Unit
Instruction
Cache
Microprocessor
RAM
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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either from collections of chips or from discrete components (transistors wired one at a
time). The 4004 powered one of the first portable electronic calculators. It was as powerful
as ENIAC which had 18000 tubes and occupied a large room. It cost less then $100. Its
targeted use was of calculation. It consisted of 2250 transistors and 16pins. Speed was 108
kHz, 60,000 ops/sec.
Why Intel came up with the idea?
A Japanese calculator manufacturer, Busicom wanted Intel to develop 16 separate IC’s
for a line of new calculators. Intel, at that point in time known only as a memory
manufacturer, was quite small and did not have the resources to do all 16 chips. Then
Ted Hoff came up with the idea of doing all 16 on a single chip. Later, Intel realized that
the 4004 could have other uses as well.
Currently Intel came with – Intel Pentium 4 (2.2GHz).
It was introduced in December 2001. It got 55 million transistors. 32-bit word size.
Within the processor it has 2 ALU’s each working at 4.4GHz. It costs around $600.
Moore’s Law
Moore's law(1965) is an empirical observation stating in effect that at our rate of
technological development and advances in the semiconductor industry the complexity
of integrated circuits doubles every 18 months. His original empirical observation was
that the number of components on semiconductor chips with lowest per-component
cost doubles roughly every 12 months, and he conjectured that the trend will stay for at
least 10 years. In 1975, Moore revised his estimate for the expected doubling time,
arguing that it was slowing down to about two years
4-, 8-, 16-, 32-, 64-bit (Word Length)
The 4004 dealt with data in chunks of 4-bits at a time
Pentium 4 deals with data in chunks (words) of 32-bit length
The new Itanium processor deals with 64-bit chunks (words) at a time
kHz, MHz, GHz (Clock Frequency)
4004 worked at a clock frequency of 108kHz
The latest processors have clock freqs. in GHz
Out of 2 microprocessors having similar designs, one with higher clock frequency will
be more powerful
Same is not true for 2 microprocessors of dissimilar designs. Example: Out of
PowerPC & Pentium 4 microprocessors working at the same freq, the former performs
better due to superior design. Same for the Athlon microprocessor when compared with
a Pentium
Enhancing the capability of a microprocessor ?
The computing capability of a microprocessor can be enhanced in many different
ways:
Evolution of Intel Microprocessors
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
38
By increasing the clock frequency
By increasing the word-width
By having a more effective caching algorithm and the right cache size
By adding more functional units (e.g. ALU’s, FPU’s, Vector/SIMD units, etc.)
Improving the architecture
What have we learnt today?
Today we learnt about the microprocessor, the key component, the brain, of a computer
We learnt about the function of a microprocessor
And its various sub-systems
Bus interface unit
Data & instruction cache memory
Instruction decoder
ALU
Floating-point unit
Control unit
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
39
Lecture 8
Binary Numbers & Logic Operations
The focus of the last lecture was on the microprocessor
During that lecture we learnt about the function of the central component of a
computer, the microprocessor
And its various sub-systems
Bus interface unit
Data & instruction cache memory
Instruction decoder
ALU
Floating-point unit
Control unit
Learning Goals for Today
To become familiar with number system used by the microprocessors - binary numbers
To become able to perform decimal-to-binary conversions
To understand the NOT, AND, OR and XOR logic operations – the fundamental
operations that are available in all microprocessors
BINARY
(BASE 2)
numbers
DECIMAL
(BASE 10)
numbers
Decimal (base 10) number system consists of 10 symbols or digits
0 1 2 3 4
5 6 7 8 9
Binary (base 2) number system consists of just two
0 1
Other popular number systems
Octal
base = 8
8 symbols (0,1,2,3,4,5,6,7)
Hexadecimal
base = 16
16 symbols (0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F)
Decimal (base 10) numbers are expressed in the
positional notation
4202 = 2x100 + 0x101 + 2x102 +
4x103
The right-most is the least significant
di i
The left-most is the most significant digit
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
40
Decimal (base 10) numbers are expressed
in the positional notation
4202 = 2x100 + 0x101 + 2x102 + 4x103
1’s multiplier
1
Decimal (base 10) numbers are expressed
in the positional notation
4202 = 2x100 + 0x101 + 2x102 + 4x103
10’s multiplier
10
Decimal (base 10) numbers are expressed in
the positional notation
4202 = 2x100 + 0x101 + 2x102 + 4x103
100’s multiplier
100
Decimal (base 10) numbers are expressed in
the positional notation
4202 = 2x100 + 0x101 + 2x102 + 4x103
1000’s multiplier
1000
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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Binary (base 2) numbers are also expressed in
the positional notation
10011=1x20+1x21+0x22+0x23+1x24
The right-most is the least significant
di i
The left-most is the most significant digit
Binary (base 2) numbers are also expressed
in the positional notation
10011=1x20+1x21+0x22+0x23+1x24
1’s multiplier
1
Binary (base 2) numbers are also expressed in
the positional notation
10011=1x20+1x21+0x22+0x23+1x24
8’s multiplier
8
Binary (base 2) numbers are also expressed in
the positional notation
10011=1x20+1x21+0x22+0x23+1x24
16’s multiplier
16
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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8.1 Why binary
Because this system is natural for digital computers
The fundamental building block of a digital computer – the switch – possesses two
natural states, ON & OFF.
It is natural to represent those states in a number system that has only two symbols, 1
and 0, i.e. the binary number system
In some ways, the decimal number system is natural to us humans. Why?
bit
binary digit
Byte = 8 bits
Decimal Binary conversion
.
Check
1001011 = 1x20 + 1x21 + 0x22 + 1x23 + 0x24 + 0x25 + 1x26
= 1 + 2 + 0 + 8 + 0 + 0 + 64
= 75
Counting in
Decimal
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
.
.
.
01
10
11
100
101
110
111
1000
1001
1010
1011
1100
1101
1110
1111
10000
10001
10010
10011
10100
10101
10110
10111
11000
11001
11010
11011
11100
11101
11110
11111
100000
100001
100010
100011
100100
.
.
.
Counting in
Binary
Convert 75 to Binary
2 75
2 37 1
2 18 1
2 9 0
2 4 1
2 2 0
2 1 0
0 1
remainde
1001011
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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That finishes our first topic - introduction to binary numbers and their conversion to
and from decimal numbers
Our next topic is …
8.2 Boolean Logic Operations
Let x, y, z be Boolean variables. Boolean variables can only have binary values i.e., they
can have values which are either 0 or 1.
For example, if we represent the state of a light switch with a Boolean variable x, we will
assign a value of 0 to x when the switch is OFF, and 1 when it is ON
A few other names for the states of these Boolean variables
0 1
Off On
Low High
False True
We define the following logic operations or functions among the Boolean
variables
Name Example Symbolically
NOT y = NOT(x) x´
AND z = x AND y x · y
OR z = x OR y x + y
XOR z = x XOR y x ⊕ y
Convert 100 to Binary
2 10
2 5 0
2 2 0
2 1 1
2 6 0
2 3 0
2 1 1
0 1
1100100
remainde
r
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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We’ll define these operations with the help of truth tables
what is the truth table of a logic function
A truth table defines the output of a logic function for all possible inputs
Truth Table for the NOT Operation
(y true whenever x is false)
X y = x´
0
1
Truth Table for the NOT Operation
X y = x´
0 1
1 0
Truth Table for the AND Operation
(z true when both x & y true)
X y z = x · y
0 0
0 1
1 0
1 1
Truth Table for the AND Operation
X y z = x · y
0 0 0
0 1 0
1 0 0
1 1 1
Truth Table for the OR Operation
(z true when x or y or both true)
x y z = x + y
0 0
0 1
1 0
1 1
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Truth Table for the OR Operation
x y z = x + y
0 0 0
0 1 1
1 0 1
1 1 1
Truth Table for the XOR Operation
(z true when x or y true, but not both)
X y z = x ⊕ y
0 0
0 1
1 0
1 1
8.3 Truth Table for the XOR Operation
X y z = x ⊕ y
0 0 0
0 1 1
1 0 1
1 1 0
Those 4 were the fundamental logic operations. Here are examples of a few more
complex situations
z = (x + y)´
z = y · (x + y)
z = (y · x) ⊕ w
8.4 STRATEGY: Divide & Conquer
z = (x + y)´
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x y x + y z = (x + y)´
0 0 0 1
0 1 1 0
1 0 1 0
1 1 1 0
z = y · (x + y)
x y x + y z = y · (x
+ y)
0 0 0 0
0 1 1 1
1 0 1 0
1 1 1 1
z = (y · x) ⊕ w
x y W y · x z = (y · x)
⊕ w
0 0 0 0 0
0 0 1 0 1
0 1 0 0 0
0 1 1 0 1
1 0 0 0 0
1 0 1 0 1
1 1 0 1 1
1 1 1 1 0
Number of rows in a truth table?
2n
n = number of input variables
What have we learnt today?
About the binary number system, and how it differs from the decimal system
Positional notation for representing binary and decimal numbers
A process (or algorithm) which can be used to convert decimal numbers to binary
numbers
Basic logic operations for Boolean variables, i.e. NOT, OR, AND, XOR, NOR,
NAND, XNOR
Construction of truth tables (How many rows?)
Focus of the Next Lecture
Next lecture will be the 3rd on Web dev
The focus of the one after that, the 10th lecture, however, will be on software. During
that lecture we will try:
To understand the role of software in computing
To become able to differentiate between system and application software
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Lecture 9
HTML Lists & Tables
(Web Development Lecture 3)
Today is our 3rd Web Dev lecture During our 2nd lecture on Web dev …
We learnt to develop our own Web pages in HTML
We learnt about some of the tags used in HTML pages
<BR>, <P>, </P>, <B>, <TITLE>, </TITLE>, <H1>, </H1>
<HTML></HTML>, <HEAD></HEAD>, <BODY></BODY>
<A HREF = “action” > label </A>, action=http:// or mailto:
We also learnt about how to upload our Web pages to VU’s Web server so that it
becomes visible on the Internet as http://www.vu.edu.pk/~xxxxxxxx/
where xxxxxxxx is your VU user ID
Today’s Lecture
We will extend our Web pages by adding a few more tags
Specifically, we will learn about various types of lists that can be added to a Web page
And also, about tables
But first …
A few comments on the general structure of HTML tags
9.1 Single Tags
<tagName>
Example: <BR>
Single Tags with Atributes
<tagName attributes>
Example: <HR width=“50%”>
Paired Tags
<tagName> … </tagName>
Example: <H1> … </H1>
Paired Tags with Attributes
<tagName attributes > … </tagName>
Example: <H1 align=“center”> … </H1>
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List
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<HTML>
<HEAD>
<TITLE>Altaf Khan's Home Page</TITLE>
</HEAD>
<BODY>
<H1>Altaf Khan</H1>
<P><B>Adjunct Lecturer in Computer Science</B><BR>
<A HREF="http://www.vu.edu.pk/">Virtual University</A><BR>
Building 1, 3rd Floor, Aiwan-e-Iqbal, Lahore<BR>
+92 42 555 1212<BR>
<A HREF="mailto:altaf@vu.edu.pk">altaf@vu.edu.pk</A><BR></P>
<P>I teach the <A HREF="http://www.vu.edu.pk/cs101/">Introduction to
Computing</A> course. </P>
</BODY>
</HTML>
<HTML>
<HEAD>
<TITLE>Altaf Khan's Home Page</TITLE>
</HEAD>
<BODY>
<H1>Altaf Khan</H1>
<P><B>Adjunct Lecturer in Computer Science</B><BR>
<A HREF="http://www.vu.edu.pk/">Virtual University</A><BR>
Building 1, 3rd Floor, Aiwan-e-Iqbal, Lahore<BR>
+92 42 555 1212<BR>
<A HREF="mailto:altaf@vu.edu.pk">altaf@vu.edu.pk</A><BR></P>
<P>I teach the <A HREF="http://www.vu.edu.pk/cs101/">Introduction to
Computing</A> course. </P>
The additional code for the list and
table goes here
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</BODY>
</HTML>
<UL> Un-ordered List
<P>My favorite PC games are:</P>
<UL>
<LI>SimCity</LI>
<LI>Quake</LI>
<LI>Bridge</LI>
</UL>
<P>My favorite sports are:</P>
<TABLE border = “1” >
<TR>
<TH>Indoor</TH>
<TH>Outdoor</TH>
</TR>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
<P>My favorite PC games are:</P>
<UL>
<LI>SimCity</LI>
<LI>Quake</LI>
<LI>Bridge</LI>
</UL>
<P>My favorite sports are:</P>
<TABLE border = “1” >
<TR>
<TH>Indoor</TH>
<TH>Outdoor</TH>
</TR>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
Additional
code
Code for
the list
Code for
the table
HTML Code
<UL>
<LI>SimCity</LI>
<LI>Quake</LI>
<LI>Bridge</LI>
</UL> • SimCity
• Quake
• Bridge
Browser Display
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<LI> Line Item
The default “bullet” for these lists is a “disc”
That, however, can be changed to a “circle” or a “square” with the help of the type
attribute
HTML Code
<UL type = “circle”>
<LI>SimCity</LI>
<LI>Quake</LI>
<LI>Bridge</LI>
</UL>
• SimCity
• Quake
• Bridge
Browser Display
Q: What happens if I start a new list without
<UL> closing the original one?
<LI>SimCity</LI>
<LI>Quake II</LI>
<UL>
<LI>SimCity 3000</LI>
<LI>Quake III</LI>
</UL>
<LI>Bridge</LI>
</UL>
• SimCity
• Quake II
• SimCity
3000
• Quake
III
• Bridge
Browser Display
Different bullets
Additional tab
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Such structures, i.e., those in which another starts before the first list is finished, are
called Nested Lists
9.2 Types of Lists
In addition to un-ordered lists, HTML supports two other types
Ordered Lists
Definition List
9.3 Ordered List Types
Type Result
“A” A, B, C, …
“a” a, b, c, …
“I” I, II, III, IV, …
“i” i, ii, iii, iv, …
“1” 1, 2, 3, …
Ordered List
<OL>
<LI>SimCity</LI>
<LI>Quake</LI>
<LI>Bridge</LI>
</OL>
1. SimCity
2. Quake
3. Bridge
Browser Display
OL instead
of UL
Numbers instead
of discs, circles or
squares
Ordered List
<OL type = “a”>
<LI>SimCity</LI>
<LI>Quake</LI>
<LI>Bridge</LI>
</OL>
a. SimCity
b. Quake
c. Bridge
Browser Display
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<DL> Definition List
<DT> Term
<DD> Definition
Q: How would one start an ordered list with
something other than 1
25. SimCity
26. Quake
27. Bridge
Browser
Display
Ordered List
<OL start = “25”>
<LI>SimCity</LI>
<LI>Quake</LI>
<LI>Bridge</LI>
</OL>
25. SimCity
26. Quake
27. Bridge
Browser Display
Definition List
<DL>
<DT>SimCity</DT>
<DD>A great
simulation
game in
which one
build cities
</DD>
<DT>Quake</DT>
<DD> One of the
best of the
shoot-em-up
genre </DD>
</DL>
SimCity
A great
simulation
game in which
one build
cities
Quake
One of the
best of the
shoot-emup
genre
Browser
Display
Ter
Definition
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Ordered lists as well as definition lists can be nested just like the un-ordered lists
Can any type of list be nested into any other type?
Lists are one way of presenting data in a an ordered or formal fashion
Tables provide another - more customizable - way of displaying ordered information
on Web pages
<TABLE> Table
(made up of rows)
<TR> Row
(made up of data cells)
<TH>
Heading Data Cell
(Can contain paragraphs, images, lists,
forms, tables)
<TD>
Data Cell
(Can contain paragraphs, images, lists,
forms, tables)
<TABLE> Attributes
BORDER
Browser Display
Squash Cricket
Indoor Outdoor
HTML Code
<TABLE border = "1" >
<TR>
<TH>Indoor</TH>
<TH>Outdoor</TH>
</TR>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
Browser Display
Squash Cricket
Indoor Outdoor
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Determines the thickness of the table border
Example: <TABLE BORDER = “2”>
CELLPADING
Determines the distance between the border of a cell and the contents of the cell
Example: <TABLE CELLPADDING = “3”>
CELLSPACING
Determines the empty spacing between the borders of two adjacent cells
Example: <TABLE CELLSPACING = “1”>
<TABLE>,<TR>,<TH>,<TD> Attributes
ALIGN
Possible values: Center, Left, Right
Example: <TH ALIGN = “center”>
BGCOLOR
Example: <TD BGCOLOR = “red”>
WIDTH
HTML Code
<TABLE border = "1" >
<TR>
<TH>Indoor</TH>
<TH>Outdoor</TH>
</TR>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
HTML Code
Squash Cricket
Indoor Outdoor
HTML Code
<TABLE>
<TR>
<TH>Indoor</TH>
<TH>Outdoor</TH>
</TR>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
Browse Display
Indoor Outdoor
Squash Cricket
50% of
the
screen
width
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Example: <TR WIDTH = “40%”>
HEIGHT
Example: <TABLE HEIGHT = “200”>
<TR> Attributes
VLAIGN
Determines the vertical alignment of the contents of all of the cells in a particular row
Possible values: Top, Middle, Bottom
Example: <TR VALIGN = “bottom”>
<TH> & <TD> Attributes
NOWRAP
Extend the width of a cell, if necessary, to fit the contents of the cell in a single line
Example: <TD NOWRAP>
COLSPAN
No. of rows the current cell should extend itself downward
Example: <TD COLSPAN = “2”>
ROWSPAN
The number of columns the current cell should extend itself
Example: <TD ROWSPAN = “5”>
VALIGN
Same as that for <TR>
Expenses Income
Year Quarter
Quetta Dubai Quetta Dubai
1 1,900 8,650 9,000 7,780
2 2,230 8,650 8,500 8,670
2001
3 4,000 8,650 9,900 9,870
HTML CODE
<TABLE border=“1” >
<TR>
<TH colspan=“2”>
Indoor Outdoor
</TH>
</TR>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
Browse Display
Indoor Outdoor
Squash Cricket
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4 2,200 8,650 9,800 9,900
1 7,780 8,650 7,780 9,000
2 8,670 8,650 8,670 8,500
3 9,870 8,650 9,870 9,900
2002
4 9,900 8,650 9,900 9,800
Must be placed
immediately after
the<TABLE> tag
9.4 Useful URL
The Table Sampler
In Today’s Lecture …
We learnt how to extend our Web pages by adding a few more tags
HTMAL Code Browser Display
<TABLE border = "1" >
<CAPTION>
My favorite sports
</CAPTION>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
My favorite sports
Squash Sports
HTMAL Code
<TABLE border = "1" >
<CAPTION>
My favorite sports
</CAPTION>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
Browser Display
My favorite sports
Squash Sports
Must be placed
immediately after
the<TABLE> tag
http://hissa.nist.gov/~black/tableQuikRef.html
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Specifically, we discussed various types of lists that can be added to a Web page – unordered,
ordered and definition lists
And also, about tables: about various tags used in a table and their associated attributes
Next Web Dev Lecture:
Interactive Forms
We will try to understand the utility of forms on Web pages
We will find out about the various components that are used in a form
We will become able to build a simple, interactive form
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Lecture 10
Computer Software
Lecture 8 was on the binary number system and logic operations
Learning Goals for Today
To discuss the role of software in computing systems
To learn to differentiate among software belonging to the system and application
categories
To learn about software ownership
We mentioned in Lecture 4 that at the highest level, two things are required for
computing
Hardware: The physical equipment in a computing environment such as the computer
and its peripheral devices (printers, speakers...)
Software: The set of instructions that operates various parts of the hardware. Also
termed as “computer program”
Computer Software
The HW needs SW to be useful; the SW needs HW to be useful
When the user needs something done by the computer, he/she gives instructions in the
form of SW to computer HW
These instructions need to be written in a language that is readily understood by
computer uP
10.1 Machine Language
A system of codes directly understandable by a computer's CPU is termed this CPU's
native or machine language. Although machine code may seem similar to assembly language
they are in fact two different types of languages. Machine code is composed only of the
two binary digits 0 and 1.
Every CPU has its own machine language, although there is considerable overlap
between some. If CPU A understands the full language of CPU B it is said that A is
compatible with B. CPU B may not be compatible with CPU A, as A may know a few
codes that B does not.
10.2 Language Translators
Human programmers write programs in a language that is easy to understand for them.
They use language translators to convert that program into machine language. It
converts the human understandable code in uPs understandable code, i.e. a language that
is easy to understand for the uPs
10.3 Software Development
A software development process is a process used to develop computer software. It
may be an ad hoc process, devised by the team for one project, but the term often refers
to a standardised, documented methodology which has been used before on similar
projects or one which is used habitually within an organisation.
The SW development process involves many steps, and coding, that is typing the
instructions in a high-level language is only a small part of that process – taking-up only
around 15% of the effort
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10.4 Major Types of SW
System SW
System software is responsible for controlling, integrating, and managing the individual
hardware components of a computer system.
System software performs tasks like transferring data from memory to disk, or rendering
systems, device drivers, compilers, assemblers, linkers, and utilities.
Software libraries that perform generic functions also tend to be regarded as system
software. System software stored on non-volatile storage on integrated circuits is usually
termed firmware. These generally perform the background tasks in a computer. These
programs, many times, talk directly to the HW.
Application SW
Programs that generally interact with the user to perform work that is useful to the user.
These programs generally talk to the HW through the assistance of system SW.
10.5 System SW are programs that …
Control the overall operation of the computer
OS
Interact directly with HW
Device drivers
Perform system management & maintenance
Utilities
Are used to develop or maintain other programs
Language translators
10.6 Operating System
Concept&Feasibility
User Requirements
Developer Specs
Planning
Design
Implementation
The Software Development Process
Hardware
Operating System
Utility Language
Translator
Device Driver
Scientific
Apps.
Business
Apps.
Productivity
Apps.
Entertainment
Apps.
System software
Application software
text onto a display specific kinds of system software include loading programs, operating
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It performs its work invisibly to control the internal functions of a computer, e.g.
maintaining files on the disk drive, managing the screen, controlling which tasks the uP
performs and in what order. It interacts directly with the computer HW. Other SW
normally does not directly interact with the HW, e.g.
Windows Mac OS Linux
UNIX Solaris DOS
CP/M VMS Firmware
ROM is a component of OS that permanently stored on a chip. It is a firm ware
program. When a computer is powered-on, it is the first program that it always executes.
Firmware consists of startup and a few low-level I/O routines that assist the computer
in finding out and executing the rest of the OS. On IBM-compatible PC’s, it is called
BIOS
10.7 Utilities:
It is a small program that provides an addition to the capabilities provided by the
operating system. In some usages, a utility is a special and nonessential part of the
operating system. These are the computer programs that perform a particular function
related to computer system management and maintenance
Examples:
1. Anti-virus SW
2. Data compression SW
Disk optimization SW
Disk backup SW
10.8 Language Translators
Programs that take code written in a HLL and translate it into a low-level language that
is easily understood by the uP
1. Compiler translates the program written in a HLL in one go. The translated code is
then used by the uP whenever the program needs to be run
2. Interpreter translates the HLL program one statement at time. It reads a single
statement, translates it into machine language and passes that machine language code to
the uP and then translates the next statement, and so on …
10.9 Device Drivers
A device driver, often called a driver for short, is a computer program that is intended
to allow another program (typically, an operating system) to interact with a hardware
device. Think of a driver as a manual that gives the operating system (e.g., Windows)
instructions on how to use a particular piece of hardware.
A device driver essentially converts the more general input/output instructions of the
operating system to messages that the device type can understand.
10.10 Application SW
Application SW are programs that interact directly with the user for the performance of
a certain type of work
Scientific/engineering/graphics SW
Mathematica; AutoCad; Corel Draw
Business SW
The billing system for the mobile phone company
Productivity SW
Word processors; Spreadsheets
Entertainment SW
Games
Educational SW
Electronic encyclopedias; The VU Web site
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10.11 Another way of classifying SW
Shrink-Wrapped SW
You can just go to a shop and buy it
Custom-built SW
You cannot just go to a shop and buy it; you have to find someone who can develop it
for you
Shrink-Wrapped SW
SW built in such a way that it is useful for many different users in many different ways.
Example: MS Word. Individuals use it and so do many large corporations. It is used
for writing one-page letters and also to typeset books
Custom-Built SW (1)
These SW are built for a particular organization to fulfill the needs of that particular
organization. This type of SW is expensive because the builder has to recoup costs and
make a profit from a single sale
Example: A system for predicting the preferences of the Nortwest Airline pilots
Custom-Built SW (2)
This is other type of custom built SW. The delivery time is longer. Customers get more
productivity out of it because it is built according to their exact specifications – just like a
custom-built shoe fits better, but generally is more expensive, and requires a longer
period for delivery
10.12 Who Owns Software?
Generally, although a piece of SW that is being used by millions, it is not owned by any
of them! Instead, it is owned by the maker of the SW
The makers let us use their SW but keep the ownership to themselves. When we buy a
SW package, we do not really buy it – we just buy a license that allows us to use it, the
ownership stays with the maker
However, there are variations on this theme …
10.13 Main types of SW licensees
Proprietary – Most software on a Windows PC or a Macintosh belongs to this category
Freeware – Most software on a Linux PC belongs to that category
Shareware – the category which lies between the above two categories
10.14 Proprietary SW License
Proprietary software, as defined by the Free Software Foundation, means any software
that is not free software or is only partially free. The modification, use and redistribution
Hardware
Operating System
Utility Language
Translator
Device Driver
Scientific
Apps.
Business
Apps.
Productivity
Apps.
Entertainment
Apps.
System software
Application software
are prohibited, or requires express permissions from the originator. The user needs to
pay the maker of the SW for buying a license that allows the user to use the SW
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The license, generally, does not transfer the ownership of the SW; it just allows the user
to use it. The user is legally barred from making copies of the licensed SW. Generally,
the license is for the personal use only. Most SW in use in the world is of this type.
Examples: Windows, Mac OS, MS Word, Adobe Photoshop, Norton Antivirus
Types of Proprietary Licenses
Single-user license
Multi-user license
Concurrent-user license
Site license
10.15 Freeware SW License
It is also known as “Public Domain SW”. It allows the user to free use of the SW. The
author, however, generally retains ownership. It can usually be downloaded from various
Web sites.
Examples: Linux; LaTeX; Netscape Web browser – the Navigator; MS Web browser –
the Internet Explorer
10.16 Open-Source SW License
Some authors give away the machine code only, which is extremely difficult to modify, if
at all. Others even give away the high-level language source code so that users can make
changes according to their own requirements. The later practice is called open-source
licensing.
Generally is any computer software whose source code is either in the public domain or,
more commonly, is copyrighted by one or more persons/entities and distributed under
an open-source license . Such a license may require that the source code be distributed
along with the software, and that the source code be freely modifiable, with at most
minor restrictions, such as a requirement to preserve the authors' names and copyright
statement in the code,
Examples: Linux; Netscape Navigator
10.17 Shareware SW License
Shareware is software that is distributed without payment ahead of time as is common
for proprietary software. Typically shareware software is obtained free of charge by
downloading, thus allowing one to try out the program ahead of time. A shareware
program is accompanied by a request for payment, and often payment is required per the
terms of the license past a set period of time. shareware are similar in that they can be
obtained and used without monetary cost. Usually shareware differs from open source
software in that requests of voluntary "shareware fees" are made, often within the
program itself, and in that source code for shareware programs is generally not available
in a form that would allow others to extend the program.
A shareware's program source, maintenance and extensibililty can sometimes be
negotiated for a licensing fee with the author(s) similar to standard proprietary software.
Examples: WinZip, Download Accelerator
10.18 Trialware
It is similar to shareware but difference is that the SW is usable for a short period only.
When the period is expired, it is no more in use until the license is not purchased. The
trial period may vary according to its developer. This period may range from a week to a
few months.
It can be downloaded from the Internet or alternatively.
What have we learnt today?
We have found out about the role software plays in a computing environment
We also learned to distinguish between software belonging to the system and application
categories
We also discussed the different types of software licenses
Topics of some of the future lectures
Operating system
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Application SW
Productivity SW
Word processor
Spreadsheets
Presentation making
Databases
Programming Languages
The SW development process
The Web development series of lectures is clearly focused on developing SW
Focus of the Next Lecture
The role of the OS in a computing environment
The various functions that an OS performs
The main components of an OS
Various types of OSes
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Lecture 11
Operating Systems
Focus of the last lecture: computer SW
We found out about the role SW plays in a computing environment
We learned to distinguish between SW belonging to the system & application categories
Also discussed the different types of SW licenses:
Proprietary
Free
Open source
Shareware
Trialware
Learning Goals for Today
The role of the operating system in a computing environment
The various functions that an operating system performs
The main components of an operating system
Various types of operating systems
11.1 Why Have OSes?
User/programmer convenience
Greater resource utilization
The Role of An OS
The 1st program that runs when a typical computer is turned ON, and the last one to
finish running when the computer is turned OFF.
It manages the HW and SW resources of the computer system, often invisibly. These
include the processor, memory, disk drives, etc.
It provides a simple, consistent way for applications to interact with the HW without
having to know all the details of the HW
Advantage for App. Developers
Application developers do not need to know much about the HW while they are
developing their app
They just develop with a particular OS in mind. If the OS runs on many types of
computers having different HW configurations, so will the app – without making any
HW-specific modifications in the app SW. The OS hides the HW differences from the
app
Are OS’es Essential?
No. If a computer has been designed for limited functionality (e.g. it runs just a single
program all the time as in a automatic clothes washing machine), it does not require a
traditional OS
In limited-functionality computers, an OS just adds to the overhead unnecessarily, which
impedes the computer’s performance
that is going to run
In the beginning …
A single user ran a single program ran on a single computer – there was no need for an
OS
Then came computer operators who ran multiple programs for multiple users one after
the other – still, no need for an OS
simultaneously. That’s when the need for OS’es arose for:
Managing the resources of the computers efficiently
Making use of computers convenient for users/programmers
11.2 Core Tasks of an OS
Processor management
Memory management
Device management
Storage management
In these situations, the required parts of the OS are integrated into the only program
Later computers became powerful and able to run multiple programs,
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Application Interface
User Interface
Processor Management
Memory Management
Straight forward for a single-user, single tasking
Each app must have enough private memory in which to execute
App can neither run into the private memory space of another app, nor be run into by
another app
Different types of memory (e.g. main, cache) in the system must be used properly, so
that each app can run most effectively
Storage Management
The OS manages storage through one of its sub-modules, the File Manager
A file system is a collection of directories, subdirectories, and files organized in a logical
order.
File manager maintains an index of the filenames & where they are located on the disk.
File manager make it easy to find the required file in a logical and timely fashion.
Device Management
Applications talk to devices through the OS and OS talks to and manages devices
through Device Drivers
Example: When we print to a laser printer, we do not need to know its details. All we
do is to tell the printer device driver about what needs to be printed and it takes care of
the details
Application Interface
App developers do not need to know much about the HW, especially the uP, while they
are developing their app
The OS provides all apps with a straight-forward and consistent interface to the HW
Example: An app uses the OS to store data on the disk drive. For that, the app does not
need to know about the exact physical characteristics of that drive; it just tells the OS to
do that through the app interface, and the OS takes cares of all the details of the task
User Interface
Users communicate with the computer using a consistent user interface provided by the
OS
This UI can be a command-line interface in which a user types in the commands.
Example:
copy a:/file1.html c:/file1.html
Or, it can be a graphical UI, where Windows, Icons, Menus, and a Pointing device (such
as a mouse) is used to receive and display information. Example:
With the help of the mouse, drag file1.html from drive a to drive c
11.3 OS Components
Error!
Kernel
Command
Interpreter
(Shell)
File
Manager
Device
Manager
GUI
Loader
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11.4 Kernel
The heart of the OS
Responsible for all the essential operations like basic house keeping, task scheduling, etc.
Also contains low-level HW interfaces
Size important, as it is memory-resident
11.5Types of OS’es
Classification w.r.t. the type of computers they run on and the type of applications they
support
Real-Time Operating System (RTOS)
Single-User, Single Task
Single-User, Multi-Tasking
Multi-User
RTOS (1)
Used to run computers embedded in machinery, robots, scientific instruments and
industrial systems
Typically, it has little user interaction capability, and no end-user utilities, since the
system will be a "sealed box" when delivered for use
Examples: Wind River, QNX, Real-time Linux, Real-time Windows NT
RTOS (2)
An important part of an RTOS is managing the resources of the computer so that a
particular operation executes in precisely the same amount of time every time it occurs
In a complex machine, having a part move more quickly just because system resources
are available may be just as catastrophic as having it not move at all because the system
was busy
Single-User, Single Task
OS’es designed to manage the computer so that one user can effectively do one thing at
a time
The Palm OS used in many palmtop computers (PDA’s) is an example of a single-user,
single-task OS
Single-User, Multi-Tasking
Most popular OS
Used by most all PC’s and Laptops
Examples: Windows, Mac OS, Linux
Lets a single user interact with several programs, simultaneously
Multi-User
A multi-user OS allows many users to take advantage of the computer's resources,
simultaneously
The OS must make sure that the requirements of the various users are balanced, and that
the programs they are using each have sufficient and separate resources so that a
problem with one user doesn't affect any of the other users
Examples: Linux, Unix, VMS and mainframe OS’es, such as MVS
11.6 Another Way of Classifying
Uni-processor OS’es
Designed to schedule tasks on a single uP only
Example: DOS
Multi-processor OS’es
Can control computers having multiple uPs, at times 1000’s of them
Example: Current versions of Windows, Mac OS, Linux,
Solaris
11.7 How many different OS’es are there?
100’s
OS’es from the Windows family dominate the desktops and run on millions of PC’s
OS’es from the Unix family (Unix, Linux, etc) are quite popular on servers
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There are hundreds more. Some designed for mainframes only. Some for embedded
applications only.
11.8 Comparing Popular OS’es
OS HW Stability Cost Apps. Support Security Popularity
Windows
(GUI) PC Poor $300 Huge
no. OK Poor Amazing
Mac OS
(Shell/GUI) Mac Good $60 Many OK Good Low
Linux
(Shell/GUI) Many Good Low Many Variable Good Low
Unix
(Shell/GUI) Many Excellent High Many Expensive Excellent Servers
What have we learnt today?
The role of the OS in a computing environment
The various functions that an OS performs
The main components of an OS
Various types of OS’es
Next Lecture: Application SW
We’ll learn about application SW, i.e. programs that interact directly with the user for the
performance of a certain type of work
We’ll try to become familiar with various SW used in the following application areas:
Scientific/engineering/graphics
Business
Productivity
Entertainment
Educational
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Lecture 12
Interactive Forms
(Web Development Lecture 4)
Focus of the last lecture was on HTML Lists & Tables
We learnt how to extend our Web pages by adding a few more tags
Specifically, we discussed various types of lists that can be added to a Web page – unordered,
ordered and definition lists
And also, about tables: about various tags used in a table and their associated attributes
Today’s Lecture
We will try to understand the utility of forms on Web pages
We will find out about the various components that are used in a form
We will become able to build a simple, interactive form
Interactive Forms (1)
Without forms, a Web site is “read-only” – it just provides information to the user
Forms enable the user to provide information to the Web site. For example, the user
can:
Perform searches on Web site
Give comments
Ask for info that is not available on the Website
Place order for goods and services
Interactive Forms (2)
Can be simple or very complex
Can fill a whole page or just a single line
Can contain a single element or many
Are always placed between the <BODY> and </BODY> tags of a Web page
Interactive Forms (3)
Are GUI-based
May contain:
Text fields
Check boxes
Buttons
Scrollable lists
Code for that Example
<HTML>
<HEAD>
<TITLE>Send Email to me</TITLE>
</HEAD>
A Simple
Example
of
Interactive
Forms
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<BODY>
<H1>Send Email to me</H1>
Code for the instructions
Code for the form
</BODY>
</HTML>
Code for the Instructions
<P>To send an eMail message to me:</P>
<OL>
<LI>Type your eMail address in the "From" field</LI>
<LI>Type a short message in the "Message" field</LI>
<LI>Press the "Send eMail to me" button</LI>
</OL>
Code for the Form
<FORM name="sendEmail" method="post" action="sendMailScriptURL">
Elements of the form
</FORM>
A Simple
Example
of
Interactive
Forms
A Simple
Example
of
Interactive
Forms
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12.1 Server-Side Scripts
Receive info that a user enters in a form
Process that info and take appropriate action
Examples:
CGI scripts on Unix servers
ASP scripts on Windows servers
Elements of the Form (1)
<P>From: <INPUT type="text" name=“sender" size="50"></P>
<P>Message: <INPUT type="text" name="message" size="50"></P>
<FORM name="sendEmail" method="post"
action="sendMailScriptURL">
Elements of the form
</FORM>
A Simple
Example
of
Interactive
Forms
name: Name given to the form
method: Forms can be submitted through two
alternate methods – GET & POST
when the form is being submitted
action: Specifies the URL that is accessed
Are programs that reside on Web servers
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Elements of the Form (2)
<P><INPUT type="hidden" name="receiver" value="altaf@vu.edu.pk"></P>
<P><INPUT type="hidden" name=“subject” value=“eMail from the form”></P>
<P><INPUT type="submit“ name="sendEmail" value="Send eMail to me"></P>
A Simple
Example
of
Interactive
Forms
A Simple
Example
of
Interactive
Forms
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<TEXTAREA
name=“message”
cols=“38”
rows=“6”
>
</TEXTAREA>
<FORM name="sendEmail" method="post" action=“sendMailScriptURL">
<table><tr>
<td>From: </td>
<td><INPUT type="text" name="sender" size="50"></td>
</tr><tr>
<td>To: </td>
<td><INPUT type="text" name="receiver" size="50"></td>
</tr><tr>
<td>Subject: </td>
<td><INPUT type="text" name="subject" size="50"></td>
</tr><tr>
<td valign="top">Message: </td>
<td><TEXTAREA name="message" cols="38"rows="6">
</TEXTAREA></td>
</tr><tr>
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<td colspan="2" align="right">
<INPUT type="submit" name="sendEmail" value="Send eMail">
</td>
</tr></table>
</FORM>
<INPUT
type=“text” name=“sender”
size=“50”
value=“your eMail address goes here”
Review of the Tags Used in Forms
<FORM>
name=“nameOfTheForm”
method=“get” or “post”
action=“URL”
Elements of the form
</FORM>
Single-Line Text Input Field
<INPUT
type=“text”
name=“fieldName”
size=“widthInCharacters”
maxlength=“limitInCharacters”
value=“initialDefaultValue”
>
Hidden Input
<INPUT
type=“hidden”
name=“fieldName”
value=“value”
>
Submit Button Input
<INPUT
type=“submit”
name=“buttonName”
value=“displayedText”
>
Multi-Line Text Input Area
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<TEXTAREA
name=“areaName”
cols=“widthInCharacters”
rows=“numberOfLines”
>
initial default value
</TEXTAREA>
This was a review of the new tags (and associated attributes) that we have used in today’s
examples. There are many more tags that can be used in a form.
Let us take a look at a few
<form name="login" method="post" action="loginScript">
<table><tr>
<td>User Name: </td>
<td>
<input type="text" name="userName" size="10">
</td>
</tr><tr>
<td>Password: </td>
<td>
<input type="password" name="password" size="10">
</td>
</tr><tr>
<td colspan="2" align="right">
<input type="submit" name="login" value="Log me in">
</td>
</tr></table>
</form>
Password Input Field
<INPUT
type=“password”
name=“fieldName”
size=“widthInCharacters”
maxlength=“limitInCharacters”
value=“initialDefaultValue”
>
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<form name="login" method="post" action="loginScript">
<table><tr>
<td>User Name: </td>
<td>
<input type="text" name="userName" size="10">
</td>
</tr><tr>
<td>Password: </td>
<td>
<input type="password" name="password" size="10">
</td>
</tr><tr>
<td colspan="2">
<input type="checkbox" name="remember" value="remember">
Remember my user name and password<br>
</td>
</tr><tr>
<td colspan="2">
<input type="submit" name="login" value="Log me in">
</td>
</tr></table>
</form>
12.2 Checkbox Input Element
<INPUT
type=“checkbox”
name=“checkboxName”
checked
value=“checkedValue”
>
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<form name="login" method="post" action="loginScript">
<table><tr>
<td>User Name: </td>
<td>
<input type="text" name="userName" size="10">
</td>
</tr><tr>
<td>Password: </td>
<td>
<input type="password" name="password" size="10">
</td>
</tr><tr>
<td valign="top">Logging in from:</td>
<td>
<input type="radio" name="from" value="home"> Home<br>
<input type="radio" name="from" value="office"> Home<br>
<input type="radio" name="from" value="university" checked> University
</td>
</tr><tr>
<td colspan="2" align="right">
<input type="submit" name="login" value="Log me in">
</td>
</tr></table>
</form>
12.3 Radio Button Input Element
<INPUT
type=“radio”
name=“radioButtonName”
checked
value=“selectedValue”
>
What is the difference between checkboxes and radio buttons?
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<form name="login" method="post" action="loginScript">
<table><tr>
<td>User Name: </td>
<td><input type="text" name="userName" size="10"></td>
</tr><tr>
<td>Password: </td>
<td>
<input type="password" name="password" size="10">
</td>
</tr><tr>
<td valign="top">Logging in from:</td>
<td>
<select size="2" name="from">
</select>
</td>
</tr><tr>
<td colspan="2">
<input type="submit" name="login" value="Log me in">
</td>
</tr></table>
</form>
12.4 Select from a (Drop Down) List
<SELECT
name=“listName”
size=“numberOfDisplayedChoices”
multiple
>
…
…
</SELECT>
<option value="university" selected> University </option>
<option value="office"> Office </option>
<option value="home"> Home</option>
<OPTION value=“value1”> text1 </OPTION>
<OPTION value=“value2” selected> text2 </OPTION>
<OPTION value=“value3”> text2 </OPTION>
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12.5 File Upload Input Element
<INPUT
type=“file”
name=“buttonName”
value=“nameOfSelectedFile”
enctype=“fileEncodingType”
>
<form
name=“uploadForm”
method=“post”
action=“uploadScript”
<input
type=“file”
name=“uploadFile”
enctype=“multipart/form-data”
>
<input
type=“submit”
name=“submit”
value=“Upload”
>
</form>
Reset Button Input Element
(Resets the contents of a form to default values)
<INPUT
type=“reset”
value=“dispalyedText”
>
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Today’s Lecture was the …
We looked at the utility of forms on Web pages
We found out about the various components that are used in a form
We became able to build a simple, interactive form
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Lecture 13
Application Software
The focus of the last lecture was on Operating Systems
Learning Goals for Today
To learn about application software
To become familiar with various software used in the following application areas:
e.g.
Scientific/engineering/graphics
Business
Productivity
Entertainment
Educational
13.1 Two Major Types of Software
System Software
Application Software
13.2 Application Software
Application software are programs that interact directly with the user
They generally do not talk directly to the hardware
13.3 Classification According to the Mode
Interactive-mode
The user runs the program on the computer and keeps on interacting with the computer
while the program runs
Example: Word processor
Batch-mode
The user starts the program and the computer processes the provided data and produces
results without any further intervention of from the user
Example: Payroll
13.4 Classification According to Application Area
Scientific/engineering/graphics
Business
Productivity
Entertainment
Educational
13.5 Scientific/Engineering/Graphics Apps
Key feature: Intense floating-point calculations
Scientific/engineering/mathematical apps
Computers initially were designed just to run them
Hardware
Operating System
Utility Language
Translator
Device Driver
Scientific
Apps.
Business
Apps.
Productivity
Apps.
Entertainment
Apps.
System software
Application software
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Generally designed for specialists
Rudimentary UI’s
Many run in batch mode
13.6 Scientific SW
Simulation of natural systems
Deforestation and effect on green-house gases
Simulation of artificial systems
NeuralWare (Simulator for artificial neural networks)
Thermo-nuclear explosions
Mathematical computation packages
Mathematica (can do hundreds, if not thousands of functions, e.g. solving a differential
eq, symbolically)
MathCAD
13.7 Engineering SW
Computer-aided design (CAD)
AutoCAD
SPICE
Virtual wind tunnels
Computer-aided manufacturing (CAM)
Telecommunication system SW
Centrex
Industrial control SW
13.8 Graphics & Animation SW (1)
Two types:
1. Vector graphics
Treats everything that is drawn as an object
Objects retain their identity after they are drawn
These objects can later be easily moved, stretched, duplicated, deleted, etc
Are resolution independent
Relatively small file size
Example: MS Visio, Corel Draw, Flash
Graphics & Animation SW (2)
2. Bit-mapped or raster graphics
Treats everything that is drawn as a bit-map
If an object is drawn on top of another, it is difficult to move just 1 of them while
leaving the other untouched
Changing the resolution often requires considerable touch-up work
Relatively large file size
Example: MS Paint, Adobe Photoshop
13.9 Business Applications
Most of the SW being developed today belongs to this category
SW that is required to run most any sort of biz:
Payroll
General ledger
Order entry
Accounts receivable & accounts payable
Inventory control
Let’s now discuss a few business SW categories which are not that common, but are
becoming more and more popular with time
13.10 E-Commerce Software
Key requirements:
Reliability
Security
Moving
graphics
e.g. cartoons
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Ability to handle 1000’s of transactions, simultaneously
13.11 ERP (Enterprise Resource Planning) SW
Very large scale, complex & expensive SW
Ties together all key activities & major systems of an organization into a single SW
system
Key benefit: Optimization of the business processes of an organization as a single system
instead of many loosely-related stand-alone systems
Example: SAP, Oracle, PeopleSoft, Baan
13.12 DSS (Decision Support Systems) SW
Sometimes also called “expert systems”
Many times are based on a branch of computer science called “artificial intelligence”
This category of SW is designed to help business managers in making effective decisions
in complex situations based on the analysis of the relevant data
13.13 Productivity SW
Most popular category in terms of licenses sold
Common features
Ability to simplify, automate everyday business tasks
Highly interactive and user-friendly design
Designed to run on PC’s
Most users do not use 90% of the SW features
Popular productivity SW
Word Processing -- Spreadsheets
Presentations -- Databases
13.14 Word Processors
Probably the most popular productivity app
Initially designed as a replacement for the typewriter
Automation
Automatic end-of-line soft carriage return
Style sheets
Table of contents & index
Spelling & grammar checking
Two approaches: WYSIWYG (e.g. Word, WordPerfect, Star) or traditional markup
(LaTeX)?
Desktop publishing
13.15 Web Page Development SW
Web pages can be developed using a simple plain-text editor like the “notepad”, but
more efficient, easy-to-use HTML editors can make the process quicker
Some of them are WYSIWYG (i.e. you don’t really need to know any HTML to use
them), others are not, while some provide both types of interfaces (DreamWeaver)
Most popular word processors now come with a built-in Web page development facility
13.16 Spreadsheet SW (1)
Electronic replacement for ledgers
Is used for automating engineering, scientific, but in majority of cases, business
calculations
A spreadsheet - VisiCalc - was the first popular application on PC’s.
It helped in popularizing PC’s by making the task of financial-forecasting much simpler,
allowing individuals to do forecasts which previously were performed by a whole team
of financial wizard
13.17 Spreadsheet SW (2)
Consist of cells arranged in rows and columns
Each cell may contain numeric values, text or formulas
Automation
Recalculations
Charts
13.18 Presentation Development SW
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Used to prepare multimedia material for lectures & presentations to display key points,
graphics, animation, or video with the help of multimedia projectors
Have replaced acetate films (slides) that were used with over-head projectors
Key advantage over acetate slides:
Easy to modify
Can be sent electronically
Its multimedia nature makes it more interesting for the audience
13.19 Small-Scale Databases SW (1)
Easy to use applications designed for efficient storage and fast and easy retrieval of data
That data may be in the form of numbers, text, or even multimedia, i.e. sounds, graphics,
animation, video
13.20 Small-Scale Databases SW (2)
Before the advent of the currently popular “relational” database model, the databasing
function was performed using what is called the “flat-file” model
That model is not very efficient for storing and searching in large databases
A database consists of a file or a set of files. Information in these is stored in the form
of records, and the records are further subdivided into fields
13.21 Productivity SW Suites
A set of stand-alone productivity applications designed to work easily with each other
Share a common UI
Are available as a bundle along with additional useful utilities
Examples: MS Office, Corel WordPerfect Office, Lotus SmartSuite, Star Office
SW Suites for other app areas are available as well, e.g. the Adobe suite of graphics apps
13.22 Document-Centered Computing (DCC) - 1
The increasing cooperation among the apps included in productivity suites has given rise
to a new computing paradigm called DCC
DCC implies that instead of developing parts of a doc in a number of apps, and then
cutting-&-pasting them to form the final doc, you stay in a single doc and call-up
appropriate apps to insert the required objects
13.23 Document-Centered Computing (DCC) - 2
Let’s say that we want to write a letter containing a map, a table and a graph
We can:
Launch the WP and type the text in
Insert a drawing by calling up the drawing toolbar app (without leaving the WP) & draw
the map
Insert a table by calling up the spreadsheet app (without leaving the WP) & build the
table
Insert a graph based on that table using the same spreadsheet app without leaving the
WP
13.24 Entertainment SW
Key feature: Simple, intuitive, many times social UI’s
The user is generally assumed to know nothing about computers
Both Microsoft & Apple are pursuing a PC-as-a-personal-entertainment-hub strategy.
Probable result: Already popular entertainment SW will become even more popular
13.25 Music & Video Players
Music players (WinAmp)
Video/Music players (Real player, Windows Media player, QuickTime player)
The Web Browsers can also display video, animation, and play music with the help of
helper applications like Flash
13.26 Music Generation & Movie Editing SW
A PC can be made the hub of a music making studio with help of appropriate HW &
SW
Inexpensive, easy-to-use video editing SW has recently become available for the iMac
13.27 Games
Many types
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Educational (especially for toddlers)
Strategy/Simulation
Sports
Shoot’em ups
The saddest aspect: You do not need any opponents or partners to play computer
games
The application SW category that provides the toughest challenge for computer HW
13.28 Educational SW
Category with probably the highest growth rate
Current focus on augmenting traditional training and education methods, but it is
shifting towards replacing traditional methods
13.29 Electronic Encyclopedias
Great resource of useful information presented in a very interesting format
Superior to the paper-based version because:
Access speed is dramatically higher
Can contain animation and sound
Much lower cost as thousand’s of pages in dozens of volumes have been replaced by a
couple of CD’s
13.30 On-Line Learning
With time, the VU Web site will become more and more focused on interactive online
learning
The Website of our textbook “Understanding Computers” is an example of an on-line
learning Website
Key features of good online learning SW:
The student can learns at his or her own pace
The student can select his or her own hours
13.31 Interactive CD’s
Same as on-line learning, but through a CD instead of a Web site
Key advantage:
Ideal for students with slow Internet access
13.32 Attributes of Good Application Software
Easy to install, un-install
User Interface
Consistent
Intuitive
Configurable
Adapts to the users need
Has a tutorial and a complete help manual
Does not have any critical bugs
13.33 Most Popular Application Software Categories
Web browsers
Email clients
Word processors
What have we learnt today?
Application software are programs that interact directly with the user for the
performance of a certain type of work
That work generally falls into one of the following usage areas
Scientific/engineering/graphics
Business
Productivity
Entertainment
Educational
Focus of the Next Lecture
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Next lecture will be the first among the four lectures that we plan to have on
productivity SW
That first lecture will be on word processing
We’ll learn about what we mean by word processing
We’ll discuss the usage of various functions provided by common word processors
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Lecture 14
Word Processing
Focus of the last lecture was on Application SW
Application SW are programs that interact directly with the user for the performance of
a certain type of work
That work generally falls into one of the following usage areas
Scientific/engineering/graphics
Business
Productivity
Entertainment
Educational
Today’s Lecture
First among the four lectures that we plan to have on productivity software, a subcategory
of application software
This first lecture will be on word processing
We’ll learn about what we mean by word processing and also desktop publishing
We’ll discuss the usage of various functions provided by common word processors
Word Processing
The art and science of converting written information into a form that looks pleasing
when printed
One of the most popular activities on the PC
14.1 Word Processor
The tool used to perform word processing
Long time ago, a word processor was a HW/SW combination used solely for performing
the word processing task. It looked like a computer terminal or a PC, but could do only
one task – word processing
Today, the term “word processor” generally means the SW used on a computer to
perform the task of word processing
Uses of Word Processors
Write a letter
Address labels
Research paper or report
Advertisement
Newsletter
Magazines
Book
And thousands of other tasks
Common Features
Type, cut, copy, paste, move text
Automatic line-breaks
Change font type, face, size, color
Change number of columns
Adjust margins and line, word, letter spacing
Have running headers, footers, page nos.
Insert tables, charts, graphics, drawings
Evolution of WP’s
Manual & electric typewriters (1930-1960)
Were page oriented
Type face/size was changed by replacing the typing ball
Typewriters with magnetic storage (1960’s)
IBM added storage capability using magnetic tape
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Line editors on computers(1960's)
Stand alone word processors (1960's-1970's)
cost: $15,000 to 20,000
Current WP programs on uCs (1980's onwards)
14.2 Types: WYSIWYG-based & Markup-based
All early WP’s and some of the modern ones as well are markup-based: similar to
HTML
Generally are harder to learn, but may provide better control and smaller file size
Example: LaTeX
Most current PC-based WP’s belong to the WYSIWYG category
Easy to get started due to the WIMP interface
Example: MS Word, Corel WordPerfect, Sun Star
14.3 Desktop Publishing (DTP)
A combination of word processing and graphic design. Used to develop elegant
documents
In the olden times, DTP was used for designing magazines, newspapers & other
professional-looking items
These days, because of the low cost of DTP SW, it is being used for less-demanding and
ordinary tasks as well
The original Macintosh PC started the era of DTP or “Personal Publishing” in 1984
DTP –vs– WP
The difference between the two is diminishing with time
Most WP’s now include many tools that, not long ago, were found only in DTP SW
Generally, DTP SW is a bit more difficult to use for us common computer users,
whereas WP SW is quite user-friendly
DTP SW generally provides finer control over the design/layout of a document
DTP: Requirements
High-end PC with a large-screen monitor
Laser printer
Scanner
DTP SW
Examples:
Adobe PageMaker
QuarkXPress
Corel Ventura
MS Publisher
14.4 Word Processors for the Web
Most common WP’s and DTP packages now have the Web development ability
They also include features like auto-recognition of eMail addresses and URL’s
However, specialized SW just for developing Web pages and sites is also available
Examples: DreamWeaver, FrontPage
The right font face & size for normal text
If text is too small, it becomes hard to read
Too large, wastage of space is the result. Plus the reader has to turn more pages than
necessary
Either way, the reader gets annoyed
For general WP, 10-12 point size works well
Most users, either use the Times New Roman or Arial/Helvetica type face
Bold, Italic, Underlined Text
Bold – fat
Italic – slanted (Why the name italic?)
Underlined
All used to emphasize a certain segment of text
Plea:
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Please do not over-do them
Their over-use makes it very difficult for the reader
And please, use one at a time: Text that is no only bold but also italic & underlined looks
+ively awful
Select, Cut, Copy, Drag, Paste
Just select and cut or copy or drag
Can also paste after a cut or a copy
Just think about the pain that people suffered before the advent of the modern WP’s
Movement of a single sentence from one page to another would have required re-doing
all the pages in between
Spelling & Grammar
Grammar checkers are not very helpful yet, but still useful and are improving with time
Warning: Spell checkers are not all that smart! Use them with care.
Disadvantage: My spelling ability is deteriorating day-by-day because of over-reliance on
WP spell-checkers. I am having great difficulty in writing even short-ish hand-written
notes without spelling errors
Thesaurus
My favorite tool
Helps you find synonyms and, sometimes, antonyms as well
Tables
Tables are sometimes useful for presenting info in an ordered fashion
Most WP’s provide extensive table construction & manipulation features
Graphics & Drawings
You can insert graphics that are made using other apps into a WP document
Several WP’s have a built-in drawing tool, which can be used for adding simple diagrams
(e.g. a flow chart, a simple street map) into a WP document
The Best Feature: Undo
Allows you to recover from your mistakes
Allows you to experiment without risk
Document View Mode
Most WP’s provide several ways of viewing a document
I normally work in and recommend what is known as the “Print Layout” view mode
In this view, the WP works in a true WYSIWYG mode
Print-Preview & Printing
Make sure to preview your document before printing it
Do this to make sure about the”look” of the document before it is printed
Most people these days either use inkjet printers or laser printers
Color inkjet printers cost less but are slower
B&W laser printers cost around twice as much, but are faster and generally have finer
resolution
Color laser printers are expensive
Automation
Table of contents
TOC can be automatically generated
Page nos. in the TOC get readjusted automatically
Index
Can be automatically generated
Page nos. in the index get readjusted automatically
Application of predefined styles
Change style; text changes automatically throughout the doc
Headers & Footers
Page numbers
Spelling error auto-highlight
Getting On-Screen Help
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All WP’s generally have some form of built-in help mechanism
To me, it seems like that many of those help-systems are designed to be “not-veryhelpful”:
they make finding answers to simple questions quite difficult
Nevertheless, do try them when you are searching for answers
14.5 Let’s try to use MS Word for creating a CV
(Remember the TOC)
Today’s Lecture was the …
First among the four lectures that we plan to have on productivity software, a subcategory
of application software
This first lecture was on word processing
We learnt about what we mean by word processing and also desktop publishing
We also discussed the usage of various functions provided by common word processors
Focus of the Next Lecture: Algorithms
To become familiar with the concept of algorithms
What they are?
What is there use?
To become able to write algorithms for simple problems
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Lecture 15
More on Interactive Forms
(Web Development Lecture 5)
Focus of the last lecture was on Interactive Forms
We looked at the utility of forms on Web pages
We found out about the various components that are used in a form
We became able to build a simple, interactive form
In Today’s Lecture …
We will learn ways of adding more interactivity to forms
We will get our first taste of JavaScript – the object-based language that we will be
employing throughout the rest of the Web development part of this course
Last time we mentioned server-side scripts; today we will write (simple) client-side scripts
in JavaScript
15.1 Single-Line Text Input Field
<INPUT
type=“text”
name=“name”
size=“widthInCharacters”
maxlength=“limitInCharacters”
value=“initialDefaultValue”
>
15.2 Password Input Field
<INPUT
type=“password”
name=“name”
size=“widthInCharacters”
maxlength=“limitInCharacters”
value=“initialDefaultValue”
>
15.3 Hidden Input
<INPUT
type=“hidden” name=“name”
value=“value”
>
15.4 Checkbox Input Element
<INPUT
type=“checkbox”
name=“name”
checked
value=“checkedValue”
>
15.5 Radio Button Input Element
<INPUT
type=“radio”
name=“name”
checked
value=“selectedValue”
>
15.6 File Upload Input Element
<INPUT
type=“file”
name=“name”
value=“nameOfSelectedFile”
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enctype=“fileEncodingType”
>
15.7 Reset Button Input Element
<INPUT
type=“reset”
value=“buttonLabel”
>
15.8 Submit Button Input
<INPUT
type=“submit” name=“name”
value=“buttonLabel”
>
8 Possible Values for the “type” Attribute of <INPUT> tag
text
password
hidden
checkbox
radio
file
reset
submit
15.9 Multi-Line Text Input Area
<TEXTAREA
name=“areaName”
cols=“width”
rows=“lines”
>
initial default value
</TEXTAREA>
15.10 Select from a (Drop Down) List
<SELECT
name=“name”
size=“numberOfDisplayedChoices”
multiple
>
<OPTION value=“value1”> text1
<OPTION value=“value2” selected> text2
<OPTION value=“value3”> text2
…
…
</SELECT>
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End of the Review of Tags Used in Forms
Now let’s take a look at a form that we constructed last time, and see how we can make
it better
Let’s now review what happens when I enter all the required info and press the “Send
eMail” button?
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This is what happens when the form is filled correctly. What if the form is filled
incorrectly?
What if the users leaves one of the essential fields, blank?
What if the user enters an illegal eMail address? Examples:
altaf2vu.edu.pk
bhola@hotmail.con
bhola@yahoo
A Reasonable Scenario
When the “Send eMail” button is clicked, the browser sends the data collected through
the form to a script running on the Web server
That server-side script:
receives that data
analyzes it
discovers the missing or incorrect data
sends a message back to the user’s browser stating the problem and asks the user to resend
This process …
That is the process of user:
Filling the incomplete/incorrect data
Sending it to the server
Receiving the response back from the server
Correcting and resending
is quite time-consuming and uses the server’s resources to help the user correct his
mistakes
It can really bog down the server if a large number of users are using that Web server
15.11 Client-Side Scripting is a viable alternate
In this technique, one uses the user’s browser to checking the form data
If data is missing or is incorrect, the browser can prompt the user to take corrective
action
This way, the form data is sent to the server-side script only after it has been established
that the collected data is complete and correct
15.12 Server-Side Scripts: Review
Are programs that reside on Web servers
Receive info that a user enters in a form
Process that info and take appropriate action
Examples:
CGI scripts on Unix servers
ASP scripts on Windows servers
Info contained
in the form
Acknowledgement
Message
to the
receiver’s
eMail
address
User’s
Computer
Web
Server
Server-Side
Script
Browser
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New Concept: Client-Side Scripts
Small programs that are a part of the Web page and run on the user’s (client’s) computer
They interact with the user to collect info or to accomplish other tasks
Once it has been collected, they may help pass the collected info on to a server-side
script
We’ll use JavaScript to do client-side scripting. However, there are many other languages
that can be used for that purpose, e.g. VBScript
Advantages of Client-Side Scripting
Reduced server load as it does not have to send messages to the user’s browser about
missing or incorrect data
Reduced network traffic as the form’s data is sent only once instead of many to’s and
fro’s
Disadvantages
Client-side scripts do not work with all browsers
Some user intentionally turn scripting off on their browsers
This increases the complexity of the Web page, as it now has to support both situations:
browsers with scripting capability, and those not having that capability
<INPUT
type=“submit”
name=“sendEmail”
value=“Send eMail”
>
Code for the simple “Send eMail”
button as was described during
the last Web development lecture
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This is one way of including JavaScript code in an HTML document – that is, including a
short JavaScript segment as part of an HTML tag
There are a few others as well. Let’s now find out about another.
But before we do that …
… let’s just make clear why we are interested in including JavaScript in our Web pages
15.13 Why JavaScript?
HTML is great for static Web pages; however, supports only rudimentary interactivity
through forms and hyperlinks
JavaScript can be used (along with HTML) to develop interactive content for the Web
What is JavaScript?
A programming language specifically designed to work with Web browsers
It is designed to be used for developing small programs – called scripts – that can be
embedded in HTML Web pages
JavaScript:
Is an interpreted language
Supports event-driven programming
Is object-based
Object Based?
Everything that JavaScript manipulates, it treats as an object – e.g. a window or a button
An object has properties – e.g. a window has size, position, status, etc.
Properties are modified with methods – e.g. a resize a window with resizeTo(150, 200)
<INPUT
type=“submit”
name=“sendEmail”
value=“Send eMail”
onMouseOver=
“if (document.sendEmail.sender.value.length< 1)
window.alert(‘Empty From field! Please
correct’)”
>
Additional JavaScript code for the smart
“Send eMail” button that would not allow itself
to be clicked if the “From” text field is left
<INPUT
type=“submit”
name=“sendEmail”
value=“Send eMail”
onMouseOver=
“if (document.sendEmail.sender.value.length < 1)
window.alert(‘Empty From field! Please correct’)”
>
Event
Handler
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<INPUT
type=“submit”
name=“sendEmail”
value=“Send eMail”
onMouseOver=
“if (document.sendEmail.sender.value.length < 1)
window.alert(‘Empty From field! Please correct’)”
>
<INPUT
type=“submit”
name=“sendEmail”
value=“Send eMail”
onMouseOver=“checkForm()”
>
<INPUT
type=“submit”
name=“sendEmail”
value=“Send eMail”
onMouseOver=
“if (document.sendEmail.sender.value.length < 1)
window.alert(‘Empty From field! Please correct’)”
>
checkForm()
JavaScript understands onMouseOver – it is one of the pre-defined keywords in
JavaScript
However, the case for checkForm() is different
A checkForm() function does not exist in JavaScript. Therefore, we will have to define it
ourselves
It can either be defined in the HEAD portion or BODY portion. We will do it in the
HEAD.
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We have looked at 2 techniques for embedding JavaScript code in a Web page:
1. Put the code in the tag for the “Send eMail” button - as was shown to you earlier
2. Put the checkForm() code in the HEAD portion & put the
onMouseOver=“checkForm()” attribute in the tag for the “Send eMail” button
Both perform the required function satisfactorily.
Q: Which of two techniques is better?
The “put all code in the tag” technique seems to require less code
For very short scripts, “all code in the tag” works well. However, this technique does
not work when one needs to put multiple script statements in the same tag
The “code in the HEAD portion” is more general-purpose, and the right choice for
developing larger JavaScript scripts
The main code segment that goes between the <SCRIPT>, </SCRIPT> tags in the
HEAD:
function checkForm() {
if ( document.sendEmail.sender.value.length < 1) {
window.alert( “Empty From field! Please correct” );
}
}
The JavaScript code included as an attribute of the “Send eMail” button:
onMouseOver=“checkForm()”
Today we checked if the “From” field of the form was empty
How can we modify the JavaScript code for checking if the “To” field is empty as well?
How about checking all four fields?
How about checking if the addresses given in the “From” and “To” fields are legal eMail
addresses?
Please try thinking about those possibilities?
In Today’s Lecture …
We learnt ways of constructing forms that were a bit more interactive
We got our first taste of JavaScript – the object-based language that we will be
employing throughout the rest of the Web development part of this course
Last time we mentioned server-side scripts; today we wrote (simple) client-side scripts in
JavaScript
Next (the 6th) Web Dev Lecture:
JavaScript Object, Properties, Methods
We will have a more formal introduction to JavaScript and client-side scripting
We will become able to appreciate the concept of objects in JavaScript
We will learn about the properties of those objects
We will become able to perform simple tasks through the application of methods
<HTML>
<HEAD>
<TITLE>Send an eMail</TITLE>
<SCRIPT>
function checkForm() {
if ( document.sendEmail.sender.value.length < 1) {
window.alert( “Empty From field! Please correct” );
}
}
</SCRIPT>
</HEAD>
<BODY bgcolor=“#FFFFCC”>
… body content …
</BODY>
</HTML>
JavaScript code
enclosed in the new
<SCRIPT>,</SCRIPT
> HTML tags
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Lecture 16
Algorithms
Focus of the last lecture was on Word Processing
First among the four lectures that we plan to have on productivity software, a subcategory
of application software
That first lecture was on WP
We learnt about what we mean by WP and also desktop publishing
We also discussed the usage of various functions provided by common WP’s
The Objective of Today’s Lecture
To become familiar with the concept of algorithms:
What they are?
What is their use?
What do they consist of?
What are the techniques used for representing them?
Solving Problems (1)
When faced with a problem:
We first clearly define the problem
Think of possible solutions
Select the one that we think is the best under the prevailing circumstances
And then apply that solution
If the solution woks as desired, fine; else we go back to step 2
Solving Problems (2)
It is quite common to first solve a problem for a particular case
Then for another
And, possibly another
And watch for patterns and trends that emerge
And to use the knowledge form those patterns and trends in coming up with a general
solution
Solving Problems (3)
It helps if we have experienced that problem or similar ones before
Generally, there are many ways of solving a given problem; the best problem-solvers
come-up with the most appropriate solution more often than not!
The process that can be used to solve a problem is termed as the “algorithm”
Algorithm:
Sequence of steps that can be taken to solve a given problem
Examples
Addition
Conversion from decimal to binary
The process of boiling an egg
The process of mailing a letter
Sorting
Searching
sequenscteeps
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Let us write down the algorithm for a problem that is familiar to us
Converting a decimal number into binary
16.1 Algorithm for Decimal-to-Binary Conversion
Write the decimal number
Divide by 2; write quotient and remainder
Repeat step 2 on the quotient; keep on repeating until the quotient becomes zero
Write all remainder digits in the reverse order (last remainder first) to form the final
result
Points to Note:
The process consists of repeated application of simple steps
All steps are unambiguous (clearly defined)
We are capable of doing all those steps
Only a limited no. of steps needs to be taken
Once all those steps are taken according to the prescribed sequence, the required result
will be found
Moreover, the process will stop at that point
16.2 Algorithm (Better Definition)
1st Definition:
Sequence of steps that can be taken to solve a problem
Better Definition:
A precise sequence of a limited number of unambiguous, executable steps that terminates in the
form of a solution
Three Requirements:
Sequence is:
Precise
Consists of a limited number of steps
Each step is:
Unambiguous
Executable
The sequence of steps terminates in the form of a solution
Convert 75 to Binary
2 75
37
1
2
18
1
2
9
0
2
4 1
2
2 0
2
1
0
2
0
1
1001011
remainder
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16.3 Why Algorithms are Useful?
Once we find an algorithm for solving a problem, we do not need to re-discover it the
next time we are faced with that problem
Once an algorithm is known, the task of solving the problem reduces to following
(almost blindly and without thinking) the instructions precisely
All the knowledge required for solving the problem is present in the algorithm
Why Write an Algorithm Down?
Written form is easier to modify and improve
Makes it easy when explaining the process to others
16.4 Analysis of Algorithms
Analysis in the context of algorithms is concerned with predicting the resources that re
requires:
Computational time
Memory
Bandwidth
Logic functions
However, Time – generally measured in terms of the number of steps required to
execute an algorithm - is the resource of most interest
By analyzing several candidate algorithms, the most efficient one(s) can be identified
Selecting Among Algorithms
When choosing among competing, successful solutions to a problem, choose the one which is the least
complex
This principle is called the “Ockham’s Razor,” after William of Ockham - famous 13-th
century English philosopher
Early History:
Search for a Generic Algorithm
The study of algorithms began with mathematicians and was a significant area of work
in the early years
The goal of those early studies was to find a single, general algorithm that could solve all
problems of a single type
Origin of the Term “Algorithm”
The name derives from the title of a Latin book: Algoritmi de numero Indorum
That book was a translation of an Arabic book: Al-Khwarizmi Concerning the Hindu
Art of Reckoning
That book was written by the famous 9-th century Muslim mathematician, Muhammad
ibn Musa al-Khwarizmi
16.5 Al-Khwarzmi
Al-Khwarizmi lived in Baghdad, where he worked at the Dar al-Hikma
Dar al-Hikma acquired and translated books on science and philosophy, particularly
those in Greek, as well as publishing original research
The word Algebra has its origins in the title of another Latin book which was a
translation of yet another book written by Al-Khwarzmi:
Kitab al-Mukhtasar fi Hisab al-Jabr wa'l-Muqabala
Al-Khwarizmi’s Golden Principle
All complex problems can be and must be solved
using the following simple steps:
Break down the problem into small, simple sub-problems
Arrange the sub-problems in such an order that each of them can be solved without
effecting any other
Solve them separately, in the correct order
For your own use in the future, so that you don’t have to spend the time for rethinking it
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Combine the solutions of the sub-problems to form the solution of the original problem
That was some info on history.
Now, let us to take a look at several types of algorithms & algorithmic strategies
16.6 Greedy Algorithm
An algorithm that always takes the best immediate, or local solution while finding an
answer
Greedy algorithms may find the overall or globally optimal solution for some
optimization problems, but may find less-than-optimal solutions for some instances of
other problems
KEY ADVANTAGE: Greedy algorithms are usually faster, since they don't consider the
details of possible alternatives
Greedy Algorithm: Counter Example
During one of the international cricket tournaments, one of the teams intentionally lost a
match, so that they could qualify for the next round
If they had won that particular match, some other team would have qualified
This is an example of a non-greedy algorithm
Greedy Algorithm: Example
A skier skiing downhill on a mountain wants to get to the bottom as quickly as possible
What sort of an algorithm should the skier be using?
The greedy-algorithm approach will be to always have the skies pointed towards the
largest downhill slope (dy/dx), at all times
What is the problem with that approach?
In what situations that will be the best algorithm?
In which situations would it perform poorly?
16.7 Deterministic Algorithm (1)
An algorithm whose behavior can be completely predicted from the inputs
That is, each time a certain set of input is presented, the algorithm gives the same results
as any other time the set of input is presented.
16.8 Randomized Algorithm (1)
Any algorithm whose behavior is not only determined by the input, but also values
produced by a random number generator
These algorithms are often simpler and more efficient than deterministic algorithms for
the same problem
Simpler algorithms have the advantages of being easier to analyze and implement.
16.9 Randomized Algorithm (2)
These algorithm work for all practical purposes but have a theoretical chance of being
wrong:
Either in the form of incorrect results
Or in the form of impractically long running time
Example: Monte Carlo algorithms.
16.10 Deterministic Algorithm (2)
There can be degrees of deterministic behavior: an algorithm that also uses a random
number generator might not be considered deterministic
However, if the "random numbers" come from a pseudo-random number generator, the
behavior may be deterministic
Most computing environments offer a “pseudo random number generators,” therefore,
most randomized algorithms, in practice, behave deterministically!
16.11 Heuristic
A procedure that usually, but not always, works or that gives nearly the right answer
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Some problems, such as the traveling salesman problem, take far too long to compute an
exact, optimal solution. A few good heuristics have been devised that are fast and find a
near-optimal solution more often than not
Is a heuristic, an algorithm? Yes? No? Why?
A Few Questions
Is that the best possible sequence?
How do you know?
How do I determine the best sequence?
16.12 The Brute Force Strategy (1)
A strategy in which all possible combinations are examined and the best among them is
selected
What is the problem with this approach?
A: Doesn’t scale well with the size of the problem
How many possible city sequences for n=6? For n=60? For n=600?
16.13 The Brute Force Strategy (2)
However, with the relentless increase in computing power, certain problems that – only
a few years ago - were impossible to solve with brute force, are now solvable with this
technique
16.14 A Selection of Algorithmic Application Areas
Search
Sort
Cryptography
Parallel
Numeric
Graphical
Quantum computing
Combinatory
We’ll now talk about the various ways of representing algorithms.
But, before we do that please allow me to say a few words about …
The Traveling Salesman Problem
A salesman needs
to visit each of the n
cities one after the
other and wants to
finish the trip where
it was started
Determine the
sequence of cities
such that the
traveling distance is
minimized
2
6
5
4
3
1
A possible sequence for n =
6
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Now onto Algorithm Representation
We have said enough about algorithms – their definition, their types, etc.
But, how do we actually represent them?
Generally, SW developers represent them in one of three forms:
Pseudo code
Flowcharts
Actual code
Pseudo Code
Language that is typically used for writing algorithms
Similar to a programming language, but not as rigid
The method of expression most suitable for a given situation is used:
At times, plain English
At others, a programming language like syntax
16.15 Flowchart
A graphical representation of a process (e.g. an algorithm), in which graphic objects are
used to indicate the steps & decisions that are taken as the process moves along from
start to finish
Individual steps are represented by boxes and other shapes on the flowchart, with arrows
between those shapes indicating the order in which the steps are taken
An algo. is “correct” if its:
– Semantics are
correct
– Syntax is correct
Semantics:
The concept embedded in
an algorithm (the soul!)
Syntax:
The actual representation
of an algorithm (the body!)
WARNINGS:
1. An algo. can be
syntactically correct, yet
semantically incorrect –
very dangerous
situation!
2. Syntactic correctness
is easier to check as
compared with semantic
Syntax & Semantics
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In Today’s Lecture, We …
Became familiar with the concept of algorithms:
What they are?
What is their use?
What do they consist of?
What are the techniques used for representing them?
Next Lecture: Algorithms II
We will continue our discussion on algorithms during the next lecture
In particular, we will discuss the pseudo code and flowcharts for particular problems
We will also discuss the pros and cons of these two algorithm representation techniques
i.e. pseudo code and flow charts
Start or stop
Process
Input or output
Connector
Decision
Flow line
Off-page connector
Flowchart
Elements
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Lecture 17
Algorithms II
Focus of the last lecture was on Algorithms
Became familiar with the concept of algorithms:
What they are? (SEQUENCE OF STEPS)
What is their use?
What are their types?
What are the techniques used for representing them?
Pseudo code
Flowcharts
Actual code
Today …
We will continue our discussion on algorithms that we started during the 16th lecture
In particular, we will look at the building blocks that are used in all algorithms
We will also discuss the pseudo code and flowcharts for particular problems
In addition, we will outline the pros and cons of those two techniques
17.1 Algorithm Building Blocks
All problems can be solved by employing any one of the following building blocks or
their combinations
Sequences
Conditionals
Loops
OK. Now on with the three building blocks of algorithms. First ..
Start or stop
Process
Input or output
Connector
Decision
Flow line
Off-page connector
Flowchart
Elements
This review was essential because we will be using these building blocks quite often today.
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We will now present the algorithm for a problem whose solution is familiar to us
We will first go through the problem statement and then present the algorithm in three
different formats:
Sequences
A sequence of instructions that are
executed in the precise order they
are written in:
statement block 1
statement block 2
statement block 3
statement block 1
statement block 2
statement block 3
Conditionals
Select between alternate courses of action
depending upon the evaluation of a condition
If ( condition = true )
statement block 1
Else
statement block 2
End if
statement
block 1
condition
True False
statement
block 2
Loops
Loop through a set of statements as long as
a condition is true
Loop while ( condition = true )
statement block
End Loop
True condition
False
statement
block
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1. Pseudo code
2. Flowchart
3. Actual code
Problem Statement
Convert a decimal number into binary
We did write down the pseudo code for this problem last time. Lets do it again, and in a
slightly more formal way
17.2 Solution in Pseudo Code
Let the decimal number be an integer x, x > 0
Let the binary equivalent be an empty string y
Repeat while x > 0 {
Determine the quotient & remainder of x ÷ 2
y = CONCATENATE( remainder, y )
x = quotient
}
Print y
Stop
Q: Is this the only possible algorithm for converting a decimal number into a binary
representation?
If not, then is this the best?
In terms of speed?
In terms of memory requirement?
In terms of ease of implementation?
You must ask these questions after writing any algorithm
17.3 Tips on Writing Good Pseudo Code
Convert 75 to Binary
2 75
37
1
2
18
1
2
9
0
2
4 1
2
2 0
2
1
0
2
0
1
1001011
remainder
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Use indention for improved clarity
Do not put “code” in pseudo code – make your pseudo code language independent
Don’t write pseudo code for yourself – write it in an unambiguous fashion so that
anyone with a reasonable knowledge can understand and implement it
Be consistent
Prefer formulas over English language descriptions
Does the flowchart depict the “correct” algorithm?
What do we mean by “correct”, or better yet, what do we check for “correctness”?
One way is to check the algorithm for a variety of inputs
Does it perform satisfactorily for:
x = 0 ?
negative numbers?
numbers with fractional parts?
Start
Find quotient
& remainder
of x ÷ 2
Get x
x>0 ?
Print y
S
y = CONC(remainder, x)
x = quotient
x is the decimal number
y is the binary equivalent
Flowchart of
Decimal
to Binary
Conversion
Yes No
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Strategy
<SCRIPT>
x = 75; // x is the decimal number
y = “”; // y is the binary equivalent
while ( x > 0) {
remainder = x % 2;
quotient = Math.floor( x / 2 );
y = remainder + y;
x = quotient;
}
document.write(“y = ” + y);
</SCRIPT>
Decimal to Binary Conversion in JavaScript
NOTE: Don’t worry if
you don’t understand
this code for now; you
will - later!
Another Example: Sorting
Sort the following objects w.r.t. their
heights
Expected Result
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There are many strategies for solving this problem. We demonstrate a simple one:
Repeat the following steps while the list is un-sorted:
Start with the first object in the list
Swap it with the one next to it if they are in the wrong order
Repeat the same with the next to the first object
Keep on repeating until you reach the last object in the list
Q: Is the list sorted?
A: No
Back to the Objects to be Sorted
Sorting: Step A1
Sorting: Step A1
Swap? Yes
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Sorting: Step A2
Sorting: Step A2
Swap? Yes
Sorting: Step A3
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Q: Is the list sorted?
A: No
Sorting: Step A3
Swap? No
Sorting: After Step A7
Sorting: Step B1
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Sorting: Step B1
Swap? Yes
Sorting: Step B2
Sorting: Step B2
Swap? No
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Q: Is the list sorted?
A: No
Sorting: After Step B7
Sorting: Step C1
Sorting: After Step C7
Sorting: Step C1
Swap? No
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Q: Is the list sorted?
A: Yes
STOP
Let’s now look at this same process of sorting being applied to a bigger list
---FLASH MOVIE FOR BUBBLE SORT GOES HERE---
Dim swapFlag As Boolean, list(8) As Integer
readList( list() ) ‘this needs to be defined
swapFlag = True
Do While swapFlag = True
For n = 1 To 8
If list(n) > list(n + 1) Then
temp = list(n)
list(n) = list(n + 1)
list(n + 1) = temp
swapFlag = True
End If
Next
Loop
For n = 1 To 8
Debug.Print list(n)
Next
Q: Is this the only possible algorithm for sorting a list?
A: Certainly not! In fact this one (called the “Bubble sort”) is probably the worst
(reasonable) algorithm for sorting a list – it is just too slow
You will learn a lot more about sorting in your future courses
Start
n = n+1
Get list
list
sorted?
Stop SWAP
list[n], list[n+1]
list is an array containing the heights
N is the total number of objects in the list
Flowchart for the Sorting Process
No
Yes
n = 0
list[n] >
list[n+1]?
Yes No
n>N ?
Yes
No
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17.4 Pros and Cons of Flowcharts (1)
I personally don’t find flowcharts very useful
The process of writing an algorithm in the form of a flowchart is just too cumbersome
And then converting this graphical form into code is not straight forward
However, there is another kind of flowcharts – called Structured Flowcharts – that may
be better suited for software developers
17.5 Pros and Cons of Flowcharts (2)
The good thing about flowcharts is that their symbols are quite intuitive and almost
universally understood
Their graphical nature makes the process of explaining an algorithm to one’s peers quite
straightforward
17.6 Pros and Cons of Pseudo Code (1)
Quite suitable for SW development as it is closer in form to real code
One can write the pseudo code, then use it as a starting point or outline for writing real
code
Many developers write the pseudo code first and then incrementally comment each line
out while converting that line into real code.
Introduction to Computing CS101 book HANDOUTS in pdf
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Table of Contents:
Lecture 1 .......................................................................................................... 9
Introduction ..................................................................................................... 9
Lecture 2 ........................................................................................................ 13
Evolution of Computing ................................................................................. 13
2.2 The “Turing test” ........................................................................... 13
2.3 Vacuum Tube – 1904: ...................................................................... 13
2.4 ABC – 1939 ..................................................................................... 14
2.6 ENIAC – 1946: ................................................................................ 14
2.7 Transistor – 1947............................................................................. 14
2.8 Floppy Disk – 1950.......................................................................... 14
2.9 UNIVAC 1 – 1951 ............................................................................ 14
2.11 ARPANET – 1969 ....................................................................... 15
2.12 Intel 4004 – 1971 .......................................................................... 15
2.13 Altair 8800 – 1975......................................................................... 15
2.14 Cray 1 – 1 976 .............................................................................. 16
2.15 IBM PC – 1981 ............................................................................ 16
2.16 Apple Macintosh – 1984............................................................... 16
2.17 World Wide Web -1989 ................................................................ 16
2.18 Quantum Computing with Molecules.......................................... 17
Lecture 3 ....................................................................................................... 18
3.1 Browser .......................................................................................... 18
3.2 URL................................................................................................... 18
3.3 What is a Web site?............................................................................. 18
3.4 What is Home Page of a web site? ...................................................... 19
3.5 Who invented the Web & Why? .......................................................... 19
3.6 Future of the Web: Semantic Web....................................................... 20
3.7 Useful Web page ................................................................................ 20
Lecture 4 ........................................................................................................ 21
4.1 Computer Types According to Capability............................................ 21
4.2 Supercomputers ................................................................................. 21
4.3 Mainframe Computers........................................................................ 21
4.4 Servers / Minicomputers .................................................................... 21
4.5 Desktops............................................................................................ 21
4.6 Portables............................................................................................ 21
4.7 Ranking w.r.t. installed number.......................................................... 22
4.8 All computers have the following essential hardware components:....... 22
4.9 Input Devices..................................................................................... 23
4.10 What is Port? .................................................................................... 24
4.11Many Types of Ports .......................................................................... 24
4.12 Processor.......................................................................................... 24
4.13 Memory/Storage .............................................................................. 24
4.14 Classifying Memory/Storage............................................................. 25
4.15 Output Devices................................................................................. 25
4.16 Modem............................................................................................. 25
1.1
1.2
1.3
2.5 Harvard Mark 1 – 1943:.................................................................... 14
2.10 Compiler - 1952 ........................................................................... 15
Charles Babbage (1791-1871)................................................................. 9
The Analytical Engine.......................................................................... 9
Ada, Countess of Lovelace(1815-52) ...................................................... 9
1.4 Course Contents & Structure .............................................................. 10
2.1 Turing Machine – 1936.................................................................... 13
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Lecture 5........................................................................................................27
5.1 PC Parts..............................................................................................27
5.2 Inside of the CPU ...............................................................................27
5.3 The Processor Module ........................................................................27
Lecture 6.........................................................................................................28
6.1 To develop your personal Web page ....................................................28
Lecture 7.........................................................................................................31
7.1 Microprocessor ...................................................................................31
7.2 Integrated Circuits..............................................................................31
7.3 Devices...............................................................................................31
7.4 Microprocessor system.......................................................................33
7.5 Micro-controllers ................................................................................33
7.6 The Main Memory Bottleneck ............................................................33
7.7 Cache .................................................................................................33
7.8 Microprocessors Building Blocks ........................................................34
Lecture 8.........................................................................................................39
Binary Numbers & Logic Operations ..............................................................39
8.1 Why binary .........................................................................................42
8.2 Boolean Logic Operations...................................................................43
8.3 Truth Table for the XOR Operation ....................................................45
8.4 STRATEGY: Divide & Conquer.........................................................45
Lecture 9.........................................................................................................47
HTML Lists & Tables (Web Development Lecture 3).....................................47
9.1 Single Tags .........................................................................................47
9.2 Types of Lists .....................................................................................52
9.3 Ordered List Types.............................................................................52
9.4 Useful URL ........................................................................................57
Lecture 10 .......................................................................................................59
Computer Software..........................................................................................59
10.1 Machine Language............................................................................59
10.2 Language Translators........................................................................59
10.3 Software Development.......................................................................59
10.4 Major Types of SW............................................................................60
10.5 System SW are programs that … ........................................................60
10.6 Operating System..............................................................................60
10.7 Utilities: ............................................................................................61
10.8 Language Translators........................................................................61
10.9 Device Drivers...................................................................................61
10.10 Application SW ................................................................................61
10.11 Another way of classifying SW ..........................................................62
10.12 Who Owns Software? .......................................................................62
10.13 Main types of SW licensees ..............................................................62
10.14 Proprietary SW License ....................................................................62
10.15 Freeware SW License .......................................................................63
10.16 Open-Source SW License .................................................................63
10.17 Shareware SW License .....................................................................63
10.18 Trialware .........................................................................................63
Lecture 11........................................................................................................65
Operating Systems ..........................................................................................65
11.1 Why Have OSes? ...............................................................................65
11.2 Core Tasks of an OS ..........................................................................65
11.3 OS Components ................................................................................66
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11.4 Kernel ............................................................................................... 67
11.5Types of OS’es ................................................................................... 67
11.6 Another Way of Classifying................................................................ 67
11.7 How many different OS’es are there?................................................. 67
11.8 Comparing Popular OS’es ................................................................. 68
Lecture 12....................................................................................................... 69
Interactive Forms (Web Development Lecture 4)............................................ 69
12.1 Server-Side Scripts............................................................................. 71
12.2 Checkbox Input Element .................................................................. 76
12.3 Radio Button Input Element............................................................. 77
12.4 Select from a (Drop Down) List......................................................... 78
12.5 File Upload Input Element ............................................................... 79
Lecture 13....................................................................................................... 81
Application Software....................................................................................... 81
13.1 Two Major Types of Software ............................................................ 81
13.2 Application Software ......................................................................... 81
13.3 Classification According to the Mode ................................................ 81
13.4 Classification According to Application Area ..................................... 81
13.5 Scientific/Engineering/Graphics Apps ............................................. 81
13.6 Scientific SW..................................................................................... 82
13.7 Engineering SW................................................................................ 82
13.8 Graphics & Animation SW (1) ........................................................... 82
13.9 Business Applications ....................................................................... 82
13.10 E-Commerce Software..................................................................... 82
13.11 ERP (Enterprise Resource Planning) SW ......................................... 83
13.12 DSS (Decision Support Systems) SW................................................ 83
13.13 Productivity SW............................................................................... 83
13.14 Word Processors.............................................................................. 83
13.15 Web Page Development SW............................................................. 83
13.16 Spreadsheet SW (1) .......................................................................... 83
13.17 Spreadsheet SW (2).......................................................................... 83
13.18 Presentation Development SW......................................................... 83
13.19 Small-Scale Databases SW (1) .......................................................... 84
13.20 Small-Scale Databases SW (2).......................................................... 84
13.21 Productivity SW Suites..................................................................... 84
13.22 Document-Centered Computing (DCC) - 1 ...................................... 84
13.23 Document-Centered Computing (DCC) - 2...................................... 84
13.24 Entertainment SW........................................................................... 84
13.25 Music & Video Players .................................................................... 84
13.26 Music Generation & Movie Editing SW........................................... 84
13.27 Games ............................................................................................ 84
13.28 Educational SW .............................................................................. 85
13.29 Electronic Encyclopedias ................................................................ 85
13.30 On-Line Learning ........................................................................... 85
13.31 Interactive CD’s .............................................................................. 85
13.32 Attributes of Good Application Software .......................................... 85
13.33 Most Popular Application Software Categories................................. 85
Lecture 14....................................................................................................... 87
Word Processing............................................................................................. 87
14.1 Word Processor................................................................................. 87
14.2 Types: WYSIWYG-based & Markup-based ....................................... 88
14.3 Desktop Publishing (DTP) ............................................................... 88
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14.4 Word Processors for the Web .............................................................88
14.5 Let’s try to use MS Word for creating a CV.........................................90
Lecture 15 .......................................................................................................91
More on Interactive Forms (Web Development Lecture 5) ..............................91
15.1 Single-Line Text Input Field..............................................................91
15.2 Password Input Field ........................................................................91
15.3 Hidden Input ....................................................................................91
15.4 Checkbox Input Element...................................................................91
15.5 Radio Button Input Element .............................................................91
15.6 File Upload Input Element ................................................................91
15.7 Reset Button Input Element ..............................................................92
15.8 Submit Button Input .........................................................................92
15.9 Multi-Line Text Input Area ...............................................................92
15.10 Select from a (Drop Down) List........................................................92
15.11 Client-Side Scripting is a viable alternate ..........................................94
15.12 Server-Side Scripts: Review...............................................................94
15.13 Why JavaScript? ...............................................................................96
Lecture 16 .......................................................................................................99
Algorithms......................................................................................................99
16.1 Algorithm for Decimal-to-Binary Conversion ...................................100
16.2 Algorithm (Better Definition) ..........................................................100
16.3 Why Algorithms are Useful?.............................................................101
16.4 Analysis of Algorithms.....................................................................101
16.5 Al-Khwarzmi ...................................................................................101
16.6 Greedy Algorithm............................................................................102
16.7 Deterministic Algorithm (1) .............................................................102
16.8 Randomized Algorithm (1) ..............................................................102
16.9 Randomized Algorithm (2) ..............................................................102
16.10 Deterministic Algorithm (2) ...........................................................102
16.11 Heuristic........................................................................................102
16.12 The Brute Force Strategy (1)...........................................................103
16.13 The Brute Force Strategy (2) ..........................................................103
16.14 A Selection of Algorithmic Application Areas..................................103
16.15 Flowchart ......................................................................................104
Lecture 17 .....................................................................................................106
Algorithms II ................................................................................................106
17.1 Algorithm Building Blocks ..............................................................106
17.2 Solution in Pseudo Code..................................................................108
17.3 Tips on Writing Good Pseudo Code.................................................108
17.4 Pros and Cons of Flowcharts (1).......................................................117
17.5 Pros and Cons of Flowcharts (2) ......................................................117
17.6 Pros and Cons of Pseudo Code (1) ...................................................117
17.7 Pros and Cons of Pseudo Code (2) ...................................................117
Lecture 18 .....................................................................................................118
Objects, Properties, Methods (Web Development Lecture 6).........................118
18.1 New Concept: Client-Side Scripts ....................................................119
18.2 Advantages of Client-Side Scripting .................................................119
18.3 Disadvantages.................................................................................119
18.4 JavaScript........................................................................................119
18.5 Client-Side JavaScript ......................................................................120
18.6 Properties........................................................................................121
18.7 Event Handlers ...............................................................................128
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Lecture 19..................................................................................................... 129
Programming Languages.............................................................................. 129
19.1 Batch Programs .............................................................................. 129
19.2 Event-Driven Programs .................................................................. 129
19.3 Types of Prog. Languages............................................................... 130
19.4 Programming SW Development ...................................................... 131
19.5 Object Oriented Design .................................................................. 131
19.6 Structured Design........................................................................... 131
19.7 Object-Oriented Languages............................................................ 132
Lecture 20 .................................................................................................... 133
SW Development Methodology..................................................................... 133
Lecture 21..................................................................................................... 142
Data Types & Operators (Web Development Lecture 7) ............................... 142
21.1 JavaScript Data Types.................................................................... 143
21.2 Declaring Variables........................................................................ 144
21.3 JavaScript Operators ...................................................................... 148
21.4 Comparison Operators.................................................................... 148
21.5 Logical Operators .......................................................................... 148
21.6 Elements of JavaScript Statements ................................................. 149
Lecture 22 .................................................................................................... 151
Spreadsheets................................................................................................. 151
22.1 Business Plan for a New Software Development Company .............. 151
22.2 The Structure of A Spreadsheet ....................................................... 152
22.3 Goal Seek ....................................................................................... 154
Lecture 23 .................................................................................................... 158
Flow Control & Loops (Web Development Lecture 8).................................. 158
JavaScript Variables are Dynamically Typed .......................................... 158
Lecture 24 .................................................................................................... 166
Design Heuristics......................................................................................... 166
24.1 Heuristic ........................................................................................ 166
24.2 System............................................................................................ 166
24.3 System Architecture........................................................................ 166
24.4 Heuristics for system architecting ................................................... 166
Lecture 25 .................................................................................................... 170
Web Design for Usability .............................................................................. 170
25.2 SPEED: ......................................................................................... 170
25.3 Elements of Website Design: .......................................................... 171
25.4 Website Navigation: ....................................................................... 171
25.5 A Few Navigation Design Heuristics: ............................................. 171
25.6 Navigation Design Heuristics (contd.):........................................... 171
25.7 Good designs assist the user in recovering from errors..................... 173
25.8 Assisting the User Recover from Errors: .......................................... 173
25.9 A few constructive recommendations .............................................. 173
25.10 Making Display Elements Legible:................................................ 175
25.11 Ensuring Text is Readable:............................................................ 175
25.12 Using Pictures & Illustrations: ...................................................... 176
25.13 Using Motion................................................................................ 176
Arrays (Web Development Lecture 9) ........................................................... 177
26.1 Arrays in JavaScript......................................................................... 178
26.2 Array Identifiers................................................................................ 180
26.3 The ‘length’ Property of Arrays ....................................................... 181
26.4 Array Methods: sort( ) 26.5 Sorts the elements in alphabetical order . 181
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26.6 Array Methods: reverse( ) 26.7 Reverses the order of the elements ....181
26.7 Pseudo Code...................................................................................182
Lecture 27 .....................................................................................................185
Computer Networks......................................................................................185
27.1 Private Networks.............................................................................186
27.2 Public Networks .............................................................................186
27.3 VPN: Virtual Private Network (1) ....................................................187
27.4 Network Topologies .......................................................................188
27.5 Networking Protocols .....................................................................190
27.6 Types of Communication Channels.................................................191
27.7 Network Security ............................................................................191
Lecture 28 .....................................................................................................193
Introduction to the Internet ...........................................................................193
28.1 Internet: Network of Networks ...........................................................196
28.2 Internet Networking Protocols ........................................................196
Lecture 29 .....................................................................................................199
Functions & Variable Scope (Web Development Lecture 10) .........................199
29.1 Function .........................................................................................199
29.2 Advantages of Functions .................................................................200
29.3 Function Identifiers ........................................................................201
29.4 Arguments of a Function.................................................................201
29.5 Event Handlers...............................................................................203
29.6 Scope of Variable ............................................................................204
Lecture 30 .....................................................................................................209
Internet Services............................................................................................209
30.1 Internet Addressing.........................................................................210
30.2 DNS: Domain Name System...........................................................210
30.3 Internet Services .............................................................................210
30.3 How does an eMail system work? ....................................................213
30.4 Using Instant Messaging ................................................................215
30.5 VoIP: Voice over IP.........................................................................220
Lecture 31 .....................................................................................................221
Developing Presentations..............................................................................221
31.1 Presentations: ..................................................................................221
31.2 The Structure of A Presentation: ......................................................224
31.3 Presentation Development SW:........................................................224
Lecture 32 .....................................................................................................226
Event Handling (Web Development Lecture 11)............................................226
32.1 What is Event Handling? ....................................................................228
32.2 In-Line JavaScript Event Handling :................................................229
Lecture 33 .....................................................................................................234
Graphics & Animation ..................................................................................234
33.1 Computer Graphics: ........................................................................235
33.2 Displaying Images: .........................................................................235
33.3 Pixel Colors :...................................................................................235
33.4 Color Mapping : ..............................................................................235
33.5 Dithering: .......................................................................................236
33.6 Aliasing: .........................................................................................236
33.7 Anti-Aliasing:..................................................................................236
33.8 Graphics File Formats: ....................................................................237
33.9 Vector or Object-Oriented Graphics: ...............................................237
33.10 Bit-Mapped or Raster Graphics:.....................................................237
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33.11 File Formats Popular on the Web (1): ............................................. 237
33.12 Image Processing:......................................................................... 237
33.13-D Graphics: .................................................................................. 238
33.14 Animation: .................................................................................... 238
Lecture 34 .................................................................................................... 240
Intelligent Systems ....................................................................................... 240
34.1 (Artificial) Intelligent Systems: ........................................................ 241
34.2 Fuzzy Logic: .................................................................................. 242
34.3 Robotics: ........................................................................................ 244
Lecture 35 .................................................................................................... 245
Mathematical Methods (Web Development Lecture 12)................................ 245
35.1 Problems & Solutions: .................................................................... 246
35.2 Mathematical Functions in JavaScript: ............................................ 248
Lecture 36 .................................................................................................... 251
Data Management ........................................................................................ 251
36.1 BholiBooks.com : ........................................................................... 252
36.2 Issues in Data Management:........................................................... 252
36.3 DBMS : .......................................................................................... 253
36.4 OS Independence: .......................................................................... 254
36.5 The Trouble with Flat-File Databases: ............................................ 257
Lecture 37 .................................................................................................... 259
Database Software ........................................................................................ 259
37.1 RDBMS.......................................................................................... 262
37.2 Some Terminology ......................................................................... 263
Lecture 38 .................................................................................................... 264
String Manipulations (Web Development Lecture 13) ................................... 264
38.1 String Manipulation in JavaScript.................................................... 267
Lecture 39 .................................................................................................... 274
Cyber Crime ................................................................................................. 274
39.1 07 February 2000 ............................................................................. 275
39.2 DoS Attack: A Cyber Crime............................................................ 276
39.3 More cybercrimes … ...................................................................... 276
39.4 Viruses ........................................................................................... 277
39.5 Other Virus-Like Programs............................................................. 278
Lecture 40 .................................................................................................... 279
Social Implications of Computing ................................................................. 279
40.1 Introduction ................................................................................... 280
40.2 Powerful Global Corporations ......................................................... 280
40.3 The Network Organization............................................................. 280
40.4 Working from Home ...................................................................... 281
40.5 From Mass- to Personalized-Marketing .......................................... 281
40.6 The Political Process ...................................................................... 282
Lecture 41..................................................................................................... 284
Images & Animation (Web Development Lecture 14) ................................... 284
41.1 Images in JavaScript ....................................................................... 286
41.2 Flash Animation ............................................................................. 293
Lecture 42 .................................................................................................... 294
The Computing Profession ........................................................................... 294
42.1 IT: Information Technology............................................................ 295
42.2 Organization: A Collection of Teams .............................................. 296
Lecture 43 .................................................................................................... 302
The Future of Computing ............................................................................. 302
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Lecture 44 .....................................................................................................308
Programming Methodology (Web Development Lecture 15) .........................308
44.1 Design Guidelines ...........................................................................309
44.2 Coding Guidelines ..........................................................................309
44.3 Guidelines for Developing Short Programs ......................................310
44.4 Design & Code Reviews..................................................................311
44.5 Testing & Debugging .....................................................................312
44.6 Helpful Editors ...............................................................................314
Lecture 45 .....................................................................................................316
Review & Wrap-Up .......................................................................................316
Course Objectives ..................................................................................323
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Lecture 1
Introduction
1.1. Charles Babbage (1791-1871)
Creator of the Analytical Engine - the first general-purpose digital computer (1833)
The Analytical Engine was not built until 1943 (in the form of the Harvard Mark I)
1.2. The Analytical Engine
A programmable, mechanical, digital machine
Could carryout any calculation
Could make decisions based upon the results of the previous calculation
Components: input; memory; processor; output
1.3. Ada, Countess of Lovelace(1815-52)
Babbage: the father of computing
Ada: the mother?
Wrote a program for computing the Bernoulli’s sequence on the Analytical Engine -
world’s 1st computer program
Ada: A programming language specifically designed by the US Dept of Defense for
developing military applications was named Ada to honor her contributions towards
computing
A lesson that we all can learn from Babbage’s Life
Charles Babbage had huge difficulties raising money to fund his research
As a last resort, he designed a clever mathematical scheme along with Ada, the Countess
of Lovelace
It was designed to increase their odds while gambling. They bet money on horse races
to raise enough money to support their research experiments
Guess what happened at the end? The lost every penny that they had.
Fast
Bored
Storage
Here is a fact:
In 1997 Deep Blue, a supercomputer designed by IBM, beat Gary Kasparov, the World
Chess Champion
That computer was exceptionally fast, did not get tired or bored. It just kept on
analyzing the situation and kept on searching until it found the perfect move from its
list of possible moves …
Goals for Today:
To develop an appreciation about the capabilities of computing
To find about the structure & policies of this course
It could analyze up to 300 billion chess moves in
three minutes
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CS101 Introduction to Computing
1.4 Course Contents & Structure
Course Objectives
To build an appreciation for the fundamental concepts in computing
To achieve a beginners proficiency in Web page development
To become familiar with popular PC productivity software
Readings
W
e
e
k
Lecture 1 Lecture
2
Lecture
3
Web
Dev
UC JS
Assignment
1
2
3
4
5
6
7
8 Midterm
Exam
9
10
11
12
13
14
15
Finals Week
Intro to computing
Evolution of computing
Computer organization
Building a PC
Microprocessors
Binary numbers & logic
Computer software
Operating systems
Application software
Algorithms
Flowcharts
Programming languages
Development methodology
Design heuristics
Web design for usability
Computer networks
Intro to the Internet
Internet services
Graphics & animation
Intelligent systems
Data management
Cyber crime
Social implications
The computing profession
The future of computing
Fundamental concepts
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Web page development
Web Development
The World Wide Web
Making a Web page
Lists & tables
Interactive forms
Objective & methods
Data types & operators
Flow control & loops Arrays
Built-in functions
User-defined functions
Events handling
String manipulation
Images & graphics
Programming methodology
Productivity Applications
Word processor
Spreadsheet
Presentation software
Database
Instructor:
Altaf Khan
Course Web Page:
UC - Understanding Computers (2000 ed.)
JS - Learn JavaScript in a Weekend
Reading Assignments
Please make sure to read the assigned material for each week before the commencement
of the corresponding week
Reading that material beforehand will help you greatly in absorbing with ease the matter
discussed during the lecture
Check your e-mail often for announcements related to this and other VU courses
Marks
distribution …
Assignments (15%)
Almost one every week, 13 in all
No credit for late submissions
The lowest 2 assignment grades will be dropped
Midterm Exam (35%)
During the 8th week
Duration: One hour
Will cover all material covered during the first seven weeks
Final Exam (50%)
During the 16th week
Will cover the whole of the course with a slight emphasis on the material covered after
the midterm exam
Duration: 2 hours
First Assignment
cs101@vu.edu.pk
http://vulms.vu.edu.pk/
Textbooks:
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
12
Send an email message to me at altaf@vu.edu.pk with the subject “Assignment 1” giving
me some information (in around 50 words) about what you see yourself doing ten years
from now
Go to the CS101 message board and post a message (consisting of approx. 50 words)
about how we could make the contents of this course more suitable for your individual
needs. The subject for this message should be “Assignment 1”
Consult the CS101 syllabus for the submission deadline
A suggestion about unfamiliar terms
We try not to use any new terms without explaining them first
However, it is not possible to do that all the time
If you encounter any unfamiliar terms during the lectures, please note them down and
consult the GLOSSARY provided at the end of the “Understanding Computers” text
book for their meaning
Let’s summarize the things that we have covered today?
A few things about:
the very first digital computer & its inventor
the capability of modern computers
the structure and contents of CS101
In the Next Lecture …
We’ll continue the story of the evolution of digital computers form the Analytical Engine
onwards.
We’ll discuss many of the key inventions and developments that he lead to the shape of
the current field of computing.
Homew
ork
Assign
ments
15%
Midterm
Examin
ation
35%
Final
Examin
ation
50%
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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Lecture 2
Evolution of Computing
Today’s Goal
To learn about the evolution of computing
To recount the important and key events
To identify some of the milestones in computer development
Babbage’s Analytical Engine - 1833
Mechanical, digital, general-purpose
Was crank-driven
Could store instructions
Could perform mathematical calculations
Had the ability to print
Could punched cards as permanent memory
Invented by Joseph-Marie Jacquard
2.1 Turing Machine – 1936
Introduced by Alan Turing in 1936, Turing machines are one of the key abstractions
used in modern computability theory, the study of what computers can and cannot do. A
Turing machine is a particularly simple kind of computer, one whose operations are
limited to reading and writing symbols on a tape, or moving along the tape to the left or
right. The tape is marked off into squares, each of which can be filled with at most one
symbol. At any given point in its operation, the Turing machine can only read or write
on one of these squares, the square located directly below its "read/write" head.
2.2 The “Turing test”
A test proposed to determine if a computer has the ability to think. In 1950, Alan Turing
(Turing, 1950) proposed a method for determining if machines can think. This method is
known as The Turing Test.
The test is conducted with two people and a machine. One person plays the role of an
interrogator and is in a separate room from the machine and the other person. The
interrogator only knows the person and machine as A and B. The interrogator does not
know which the person is and which the machine is.
Using a teletype, the interrogator, can ask A and B any question he/she wishes. The aim
of the interrogator is to determine which the person is and which the machine is.
The aim of the machine is to fool the interrogator into thinking that it is a person. If the
machine succeeds then we can conclude that machines can think.
2.3 Vacuum Tube – 1904:
Interrogator
asking
questions
Human
providing
answers
Computer
on its own
providing
answers
Terminal
Terminal
Computer
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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A vacuum tube is just that: a glass tube surrounding a vacuum (an area from which all
gases has been removed). What makes it interesting is that when electrical contacts are
put on the ends, you can get a current to flow though that vacuum.
A British scientist named John A. Fleming made a vacuum tube known today as a diode.
Then the diode was known as a "valve,"
2.4 ABC – 1939
The Atanasoff-Berry Computer was the world's first electronic digital computer. It was
built by John Vincent Atanasoff and Clifford Berry at Iowa State University during 1937-
42. It incorporated several major innovations in computing including the use of binary
arithmetic, regenerative memory, parallel processing, and separation of memory and
computing functions.
2.5 Harvard Mark 1 – 1943:
Howard Aiken and Grace Hopper designed the MARK series of computers at Harvard
University. The MARK series of computers began with the Mark I in 1944. Imagine a
giant roomful of noisy, clicking metal parts, 55 feet long and 8 feet high. The 5-ton
device contained almost 760,000 separate pieces. Used by the US Navy for gunnery and
ballistic calculations, the Mark I was in operation until 1959.
The computer, controlled by pre-punched paper tape, could carry out addition,
subtraction, multiplication, division and reference to previous results. It had special
subroutines for logarithms and trigonometric functions and used 23 decimal place
numbers. Data was stored and counted mechanically using 3000 decimal storage wheels,
1400 rotary dial switches, and 500 miles of wire. Its electromagnetic relays classified the
machine as a relay computer. All output was displayed on an electric typewriter. By
today's standards, the Mark I was slow, requiring 3-5 seconds for a multiplication
operation
2.6 ENIAC – 1946:
ENIAC I (Electrical Numerical Integrator And Calculator). The U.S. military sponsored
their research; they needed a calculating device for writing artillery-firing tables (the
settings used for different weapons under varied conditions for target accuracy).
John Mauchly was the chief consultant and J Presper Eckert was the chief engineer.
Eckert was a graduate student studying at the Moore School when he met John Mauchly
in 1943. It took the team about one year to design the ENIAC and 18 months and
500,000 tax dollars to build it.
The ENIAC contained 17,468 vacuum tubes, along with 70,000 resistors and 10,000
capacitors.
2.7 Transistor – 1947
The first transistor was invented at Bell Laboratories on December 16, 1947 by William
Shockley. This was perhaps the most important electronics event of the 20th century, as
it later made possible the integrated circuit and microprocessor that are the basis of
modern electronics. Prior to the transistor the only alternative to its current regulation
and switching functions (TRANSfer resISTOR) was the vacuum tubes, which could only
be miniaturized to a certain extent, and wasted a lot of energy in the form of heat.
Compared to vacuum tubes, it offered:
smaller size
better reliability
lower power consumption
lower cost
2.8 Floppy Disk – 1950
Invented at the Imperial University in Tokyo by Yoshiro Nakamats
2.9 UNIVAC 1 – 1951
UNIVAC-1. The first commercially successful electronic computer, UNIVAC I, was
also the first general purpose computer - designed to handle both numeric and textual
information. It was designed by J. Presper Eckert and John Mauchly. The
implementation of this machine marked the real beginning of the computer era.
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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Remington Rand delivered the first UNIVAC machine to the U.S. Bureau of Census in
1951. This machine used magnetic tape for input.
first successful commercial computer
design was derived from the ENIAC (same developers)
first client = U.S. Bureau of the Census
$1 million
48 systems built
2.10 Compiler - 1952
Grace Murray Hopper an employee of Remington-Rand worked on the NUIVAC. She
took up the concept of reusable software in her 1952 paper entitled "The Education of a
Computer" and developed the first software that could translate symbols of higher
computer languages into machine language. (Compiler)
2.11 ARPANET – 1969
The Advanced Research Projects Agency was formed with an emphasis towards
research, and thus was not oriented only to a military product. The formation of this
agency was part of the U.S. reaction to the then Soviet Union's launch of Sputnik in
1957. (ARPA draft, III-6). ARPA was assigned to research how to utilize their
investment in computers via Command and Control Research (CCR). Dr. J.C.R.
Licklider was chosen to head this effort.
Developed for the US DoD Advanced Research Projects Agency
60,000 computers connected for communication among research organizations and
universities
2.12 Intel 4004 – 1971
The 4004 was the world's first universal microprocessor. In the late 1960s, many
scientists had discussed the possibility of a computer on a chip, but nearly everyone felt
that integrated circuit technology was not yet ready to support such a chip. Intel's Ted
Hoff felt differently; he was the first person to recognize that the new silicon-gated MOS
technology might make a single-chip CPU (central processing unit) possible.
Hoff and the Intel team developed such architecture with just over 2,300 transistors in
an area of only 3 by 4 millimeters. With its 4-bit CPU, command register, decoder,
decoding control, control monitoring of machine commands and interim register, the
4004 was one heck of a little invention. Today's 64-bit microprocessors are still based on
similar designs, and the microprocessor is still the most complex mass-produced product
ever with more than 5.5 million transistors performing hundreds of millions of
calculations each second - numbers that are sure to be outdated fast.
2.13 Altair 8800 – 1975
By 1975 the market for the personal computer was demanding a product that did not
require an electrical engineering background and thus the first mass produced and
marketed personal computer (available both as a kit or assembled) was welcomed with
open arms. Developers Edward Roberts, William Yates and Jim Bybee spent 1973-1974
to develop the MITS (Micro Instruments Telemetry Systems ) Altair 8800. The price was
$375, contained 256 bytes of memory (not 256k),but had no keyboard, no display, and
no auxiliary storage device. Later, Bill Gates and Paul Allen wrote their first product for
the Altair -- a BASIC compiler (named after a planet on a Star Trek episode).
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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2.14 Cray 1 – 1 976
It looked like no other computer before, or for that matter, since. The Cray 1 was the
world's first "supercomputer," a machine that leapfrogged existing technology when it
was introduced in 1971.
And back then, you couldn't just order up fast processors from Intel. "There weren't any
microprocessors," says Gwen Bell of The Computer Museum History Center. "These
individual integrated circuits that are on the board performed different functions."
Each Cray 1, like this one at The Computer Museum History Center, took months to
build. The hundreds of boards and thousands of wires had to fit just right. "It was really
a hand-crafted machine," adds Bell. "You think of all these wires as a kind of mess, but
each one has a precise length."
2.15 IBM PC – 1981
On August 12, 1981, IBM released their new computer, re-named the IBM PC. The
"PC" stood for "personal computer" making IBM responsible for popularizing the term
"PC".
The first IBM PC ran on a 4.77 MHz Intel 8088 microprocessor. The PC came equipped
with 16 kilobytes of memory, expandable to 256k. The PC came with one or two 160k
Floppy Disks Drives and an optional color monitor. The price tag started at $1,565,
which would be nearly $4,000 today.
2.16 Apple Macintosh – 1984
Apple introduced the Macintosh to the nation on January 22, 1984. The original
Macintosh had 128 kilobytes of RAM, although this first model was simply called
"Macintosh" until the 512K model came out in September 1984. The Macintosh retailed
for $2495. It wasn't until the Macintosh that the general population really became aware
of the mouse-driven graphical user interface.
2.17 World Wide Web -1989
"CERN is a meeting place for physicists from all over the world, who collaborate on
complex physics, engineering and information handling projects. Thus, the need for the
WWW system arose "from the geographical dispersion of large collaborations, and the
fast turnover of fellows, students, and visiting scientists," who had to get "up to speed
on projects and leave a lasting contribution before leaving."
CERN possessed both the financial and computing resources necessary to start the
project. In the original proposal, Berners-Lee outlined two phases of the project:
First, CERN would "make use of existing software and hardware as well as
implementing simple browsers for the user's workstations, based on an analysis of the
requirements for information access needs by experiments."
Second, they would "extend the application area by also allowing the users to add new
material."
Berners-Lee expected each phase to take three months "with the full manpower
complement": he was asking for four software engineers and a programmer. The
proposal talked about "a simple scheme to incorporate several different servers of
machine-stored information already available at CERN."
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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Set off in 1989, the WWW quickly gained great popularity among Internet users. For
instance, at 11:22 am of April 12, 1995, the WWW server at the SEAS of the University
of Pennsylvania "responded to 128 requests in one minute. Between 10:00 and 11:00
2.18 Quantum Computing with Molecules
by Neil Gershenfeld and Isaac L. Chuang
Factoring a number with 400 digits--a numerical feat needed to break some security
codes--would take even the fastest supercomputer in existence billions of years. But a
newly conceived type of computer, one that exploits quantum-mechanical interactions,
might complete the task in a year or so, thereby defeating many of the most
sophisticated encryption schemes in use. Sensitive data are safe for the time being,
because no one has been able to build a practical quantum computer. But researchers
have now demonstrated the feasibility of this approach. Such a computer would look
nothing like the machine that sits on your desk; surprisingly, it might resemble the cup of
coffee at its side.
Several research groups believe quantum computers based on the molecules in a liquid
might one day overcome many of the limits facing conventional computers. Roadblocks
to improving conventional computers will ultimately arise from the fundamental physical
bounds to miniaturization (for example, because transistors and electrical wiring cannot
be made slimmer than the width of an atom). Or they may come about for practical
reasons--most likely because the facilities for fabricating still more powerful microchips
will become prohibitively expensive. Yet the magic of quantum mechanics might solve
both these problems.
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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Lecture 3
Today’s Goal is to …
Become familiar with the World Wide Web
Become familiar with the Web’s structure and how the Web works
Learn about its genesis, its evolution, and its future
About its impact on computing, society, commerce
3.1 Browser
A browser is an application program that provides a way to look at and interact with all
the information on the World Wide Web. The word "browser" seems to have originated
prior to the Web as a generic term for user interfaces that let you browse (navigate
through and read) text files online. By the time the first Web browser with a graphical
user interface was generally available (Mosaic, in 1993), the term seemed to apply to Web
content, too. Technically, a Web browser is a client program that uses the Hypertext
Transfer Protocol (HTTP) to make requests of Web servers throughout the Internet on
behalf of the browser user.
3.2 URL
URL (Uniform Resource Locator, previously Universal Resource Locator) - pronounced
YU-AHR-EHL or, in some quarters, UHRL - is the address of a file (resource)
accessible on the Internet. The type of file or resource depends on the Internet
application protocol. Using the World Wide Web's protocol, the Hypertext Transfer
Protocol (HTTP), the resource can be an HTML page (like the one you're reading), an
image file, or any other file supported by HTTP. The URL contains the name of the
protocol required to access the resource, a domain name that identifies a specific
computer on the Internet, and a pathname (hierarchical description of a file location) on
the computer.
On the Web (which uses the Hypertext Transfer Protocol), an example of a URL is:
http://www.ietf.org/rfc/rfc2396.txt
Which describes a Web page to be accessed with an HTTP (Web browser) application
that is located on a computer named www.ietf.org. The pathname for the specific file in
that computer is /rfc/rfc2396.txt.
An HTTP URL can be for any Web page, not just a home page, or any individual file.
Examples:
http://dawn.com
http://www.vu.edu.pk
http://www.smeda.org.pk
3.3 What is a Web site?
A Web site is a related collection of World Wide Web (WWW) files that includes a
beginning file called a home page. A company or an individual tells you how to get to
their Web site by giving you the address of their home page. From the home page, you
can get to all the other pages on their site. For example, the Web site for IBM has the
home page address of http://www.ibm.com. IBM's home page address leads to
thousands of pages but a web site can also be just of few pages.
http://www.vu.edu.pk/
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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3.4 What is Home Page of a web site?
1) For a Web user, the home page is the first Web page that is displayed after starting a
Web browser like Netscape's Navigator or Microsoft's Internet Explorer. The browser is
usually preset so that the home page is the first page of the browser manufacturer.
However, you can set it to open to any Web site. For example, you can specify that
"http://www.yahoo.com" or "http://whatis.com" be your home page. You can also
specify that there be no home page (a blank space will be displayed) in which case you
choose the first page from your bookmark list or enter a Web address.
2) For a Web site developer, a home page is the first page presented when a user selects
a site or presence on the World Wide Web. The usual address for a Web site is the home
page address, although you can enter the address (Uniform Resource Locator) of any
page and have that page sent to you.
3.5 Who invented the Web & Why?
"CERN is a meeting place for physicists from all over the world, who collaborate on
complex physics, engineering and information handling projects. Thus, the need for the
WWW system arose "from the geographical dispersion of large collaborations, and the
fast turnover of fellows, students, and visiting scientists," who had to get "up to speed
on projects and leave a lasting contribution before leaving."
CERN possessed both the financial and computing resources necessary to start the
project. In the original proposal, Berners-Lee outlined two phases of the project:
First, CERN would "make use of existing software and hardware as well as
implementing simple browsers for the user's workstations, based on an analysis of the
requirements for information access needs by experiments."
Second, they would "extend the application area by also allowing the users to add new
material."
Berners-Lee expected each phase to take three months "with the full manpower
complement": he was asking for four software engineers and a programmer. The
proposal talked about "a simple scheme to incorporate several different servers of
machine-stored information already available at CERN."
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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Set off in 1989, the WWW quickly gained great popularity among Internet users. For
instance, at 11:22 am of April 12, 1995, the WWW server at the SEAS of the University
of Pennsylvania "responded to 128 requests in one minute. Between 10:00 and 11:00
3.6 Future of the Web: Semantic Web
The Semantic Web is an idea of World Wide Web inventor Tim Berners-Lee that the
Web as a whole can be made more intelligent and perhaps even intuitive about how to
serve a user's needs. Berners-Lee observes that although search engines index much of
the Web's content, they have little ability to select the pages that a user really wants or
needs. He foresees a number of ways in which developers and authors, singly or in
collaborations, can use self-descriptions and other techniques so that contextunderstanding
programs can selectively find what users want.
3.7 Useful Web page
Web page for our “Understanding Computers” text book
http://www.hbcollege.com/infosys/parker2000
What have we learnt today?
What is the World Wide Web?
How does it work?
About its expected evolution into the Semantic Web
The impact of the Web on computing, society, and commerce
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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Lecture 4
Today’s Goal
To learn to classify computers according to their capability and targeted applications
To find out about the essential building blocks that make up a modern computer
Computer Types According to Capability
4.1 Computer Types According to Capability
4.2 Supercomputers
A supercomputer is a computer that performs at or near the currently highest
operational rate for computers. A supercomputer is typically used for scientific and
engineering applications that must handle very large databases or do a great amount of
computation (or both). At any given time, there are usually a few well-publicized
supercomputers that operate at the very latest and always incredible speeds.
Perhaps the best-known builder of supercomputers has been Cray Research, now a part
of Silicon Graphics. Some supercomputers are at "supercomputer center," usually
university research centers, some of which, in the United States, are interconnected on
an Internet backbone (A backbone is a larger transmission line that carries data gathered
from smaller lines that interconnect with it) known as vBNS or NSFNet.
At the high end of supercomputing are computers like IBM's "Blue Pacific," announced
on October 29, 1998. Built in partnership with Lawrence Livermore National Laboratory
operations per second), 15,000 times faster than the average personal computer. It
consists of 5,800 processors containing a total of 2.6 trillion bytes of memory and
interconnected with five miles of cable.
4.3 Mainframe Computers
A very large and expensive computer capable of supporting hundreds, or even
thousands, of users simultaneously. In the hierarchy that starts with a simple
microprocessor (in watches, for example) at the bottom and moves to supercomputers at
the top, mainframes are just below supercomputers. In some ways, mainframes are more
powerful than supercomputers because they support more simultaneous programs. But
supercomputers can execute a single program faster than a mainframe. The distinction
between small mainframes and minicomputers is vague (not clearly expressed),
depending really on how the manufacturer wants to market its machines.
4.4 Servers / Minicomputers
A midsized computer. In size and power, minicomputers lie between workstations and
mainframes. In the past decade, the distinction between large minicomputers and small
mainframes has blurred, however, as has the distinction between small minicomputers
and workstations. But in general, a minicomputer is a multiprocessing system capable of
supporting from 4 to about 200 users simultaneously.
4.5 Desktops
These are also called microcomputers. Low-end desktops are called PC’s and high-end
ones “Workstations”. These are generally consisting of a single processor only, some
times 2, along with MB’s of memory, and GB’s of storage. PC’s are used for running
productivity applications, Web surfing, messaging. Workstations are used for more
demanding tasks like low-end 3-D simulations and other engineering & scientific apps.
These are not as reliable and fault-tolerant as servers. Workstations cost a few thousand
dollars; PC around a $1000.
4.6 Portables
Portable computer is a personal computer that is designed to be easily transported and
relocated, but is larger and less convenient to transport than a notebook computer. The
earliest PCs designed for easy transport were called portables. As the size and weight of
most portables decreased, they became known as laptop computer and later as notebook
computer. Today, larger transportable computers continue to be called portable computers.
Most of these are special-purpose computers - for example, those for use in industrial
environments where they need to be moved about frequently.
in California, Blue Pacific is reported to operate at 3.9 teraflop (trillion floating point
Introduction to Computing –CS101 VU
© Copyright Virtual University of Pakistan
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PDA (personal digital assistant) is a term for any small mobile hand-held device that
provides computing and information storage and retrieval capabilities for personal or
business use, often for keeping schedule calendars and address book information handy.
The term handheld is a synonym. Many people use the name of one of the popular PDA
products as a generic term. These include Hewlett-Packard's Palmtop and 3Com's
PalmPilot.
Most PDAs have a small keyboard. Some PDAs have an electronically sensitive pad on
which handwriting can be received. Apple's Newton, which has been withdrawn from
the market, was the first widely-sold PDA that accepted handwriting. Typical uses
include schedule and address book storage and retrieval and note-entering. However,
many applications have been written for PDAs. Increasingly, PDAs are combined with
telephones and paging systems.
Some PDAs offer a variation of the Microsoft Windows operating system called
Windows CE. Other products have their own or another operating system.
4.7 Ranking w.r.t. installed number
PC’s
PDA’s
Workstations
Servers
Wearable (picture is provided)
Mainframes
Supercomputers
At the highest level, two things are required for computing
Hardware
Computer equipment such as a CPU, disk drives, CRT, or printer
Software
A computer program, which provides the instructions which enable the computer
hardware to work
4.8 All computers have the following essential hardware components:
Input
The devices used to give the computer data or commands are called Input devices.
Includes keyboard, mouse, scanner, etc
Processor
A processor is the logic circuitry that responds to and processes the basic instructions
that drive a computer.
The term processor has generally replaced the term central processing unit (CPU). The
processor in a personal computer or embedded in small devices is often called a
microprocessor.
Short for microprocessor, the central processing unit in a computer. The processor is the
logic of a computer and functions comparably to a human central nervous system,
directing signals from one component to another and enabling everything to happen
Memory
Memory is the electronic holding place for instructions and data that your computer's
microprocessor can reach quickly. When your computer is in normal operation, its
memory usually contains the main parts of the operating system and some or all of the
application programs and related data that are being used. Memory is often used as a
shorter synonym for random access memory (RAM). This kind of memory is located on
one or more microchips that are physically close to the microprocessor in your
computer. Most desktop and notebook computers sold today include at least 16
megabytes of RAM, and are upgradeable to include more. The more RAM you have, the
less frequently the computer has to access instructions and data from the more slowly
accessed hard disk form of storage.
Memory is also called primary or main memory.
Storage
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Computer storage is the holding of data in an electromagnetic form for access by a
computer processor. It is also called secondary storage. In secondary storage data resides
on hard disks, tapes, and other external devices.
Primary storage is much faster to access than secondary storage because of the proximity
of the storage to the processor or because of the nature of the storage devices. On the
other hand, secondary storage can hold much more data than primary storage.
Output
The devices to which the computer writes data are called Output devices. Often converts
the data into a human readable form. Monitor and printer are output devices.
4.9 Input Devices
Mouse
A mouse is a small device that a computer user pushes across a desk surface in order to
point to a place on a display screen and to select one or more actions to take from that
position. The mouse first became a widely-used computer tool when Apple Computer
made it a standard part of the Apple Macintosh. Today, the mouse is an integral part of
the graphical user interface (GUI) of any personal computer. The mouse apparently got
its name by being about the same size and color as a toy mouse.
Keyboard
On most computers, a keyboard is the primary text input device. A keyboard on a
computer is almost identical to a keyboard on a typewriter. Computer keyboards will
typically have extra keys, however. Some of these keys (common examples include
Control, Alt, and Meta) are meant to be used in conjunction with other keys just like
shift on a regular typewriter. Other keys (common examples include Insert, Delete,
Home, End, Help, function keys, etc.) are meant to be used independently and often
perform editing tasks.
Joystick
In computers, a joystick is a cursor control device used in computer games. The joystick,
which got its name from the control stick used by a pilot to control the ailerons and
elevators of an airplane, is a hand-held lever that pivots on one end and transmits its
coordinates to a computer. It often has one or more push-buttons, called switches,
whose position can also be read by the computer.
Digital Camera
A digital camera records and stores photographic images in digital form that can be fed
to a computer as the impressions are recorded or stored in the camera for later loading
into a computer or printer. Currently, Kodak, Canon, and several other companies make
digital cameras.
Microphone
A device that converts sound waves into audio signals. These could be used for sound
recording as well as voice chatting through internet.
Scanner
A scanner is a device that captures images from photographic prints, posters, magazine
pages, and similar sources for computer editing and display. Scanners come in hand-held,
feed-in, and flatbed types and for scanning black-and-white only, or color. Very high
resolution scanners are used for scanning for high-resolution printing, but lower
Keyboard Mouse
Memory Printer
Hard
Disk
Memory
Bus
System Bus
Monitor
Compact
Disk
Processor
Integer
Unit
Control
Unit
Cache
Memory
Floating
Point
Unit
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resolution scanners are adequate for capturing images for computer display. Scanners
usually come with software, such as Adobe's Photoshop product, that lets you resize and
otherwise modify a captured image
4.10 What is Port?
On computer and telecommunication devices, a port (noun) is generally a specific place
for being physically connected to some other device, usually with a socket and plug of
some kind. Typically, a personal computer is provided with one or more serial ports and
usually one parallel port.
4.11Many Types of Ports
Parallel
An interface on a computer that supports transmission of multiple bits at the same time;
almost exclusively used for connecting a printer. On IBM or compatible computers, the
parallel port uses a 25-pin connector.
Serial
It is a general-purpose personal computer communications port in which 1 bit of
information is transferred at a time. In the past, most digital cameras were connected to
a computer's serial port in order to transfer images to the computer. Recently, however,
the serial port is being replaced by the much faster USB port on digital cameras as well as
computers.
SCSI
A port that's faster than the serial and parallel ports but slower and harder to configure
than the newer USB port. Also know as the Small Computer System Interface.
A high-speed connection that enables devices, such as hard-disk drives and network
adapters, to be attached to a computer.
USB
USB (Universal Serial Bus) is a plug-and-play hardware interface for peripherals such as
the keyboard, mouse, joystick, scanner, printer and modem. USB has a maximum
bandwidth of 12 Mbits/sec and up to 127 devices can be attached. With USB, a new
device can be added to your computer without having to add an adapter card. It typically
is located at the back of the PC
Firewire
FireWire is simply a really fast port that lets you connect computer peripherals and
consumer electronics to your computer without the need to restart. It is a simple
common plug-in serial connector on the back of your computer.
It has the ability to chain devices together in a number of different ways without
terminators for example, simply join 2 computers with a FireWire cable for instant highspeed
networking.
4.12 Processor
Pentium
Celeron
Athlon
PowerPC
StrongARM (PDA)
Crusoe (Laptops)
SPARC (Workstations)
4.13 Memory/Storage
RAM
RAM (random access memory) is the place in a computer where the operating system,
application programs, and data in current use are kept so that they can be quickly
reached by the computer's processor. RAM is much faster to read from and write to than
the other kinds of storage in a computer, the hard disk, floppy disk, and CD-ROM.
However, the data in RAM stays there only as long as your computer is running. When
you turn the computer off, RAM loses its data. When you turn your computer on again,
your operating system and other files are once again loaded into RAM, usually from your
hard disk.
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Punch cards
A card on which data can be recorded in the form of punched holes.
ROM
ROM is "built-in" computer memory containing data that normally can only be read, not
written to. ROM contains the programming that allows your computer to be "booted
up" or regenerated each time you turn it on. Unlike a computer's random access memory
(RAM), the data in ROM is not lost when the computer power is turned off.
The ROM is sustained by a small long-life battery in your computer.
Hard disk
Hard disk is a computer storage device which saves and retrieves the data when
required. Its capacity is much greater than the computer memory (RAM, ROM). Data on
hard disk is stored and retrieved from electromagnetically charged surface.
Today we can save huge amount of data on a single hard disk. Now hard disks can
contain several billion bytes.
Floppy disk
A diskette is a random access, removable data storage medium that can be used with
personal computers. The term usually refers to the magnetic medium housed in a rigid
plastic cartridge measuring 3.5 inches square and about 2 millimeters thick. Also called a
"3.5-inch diskette," it can store up to 1.44 megabytes (MB) of data.
Tape
In computers, tape is an external storage medium, usually both readable and writable,
can store data in the form of electromagnetic charges that can be read and also erased. A
tape drive is the device that positions, writes from, and reads to the tape.
CD
A compact disc [sometimes spelled disk] (CD) is a small, portable, round medium for
electronically recording, storing, and playing back audio, video, text, and other
information in digital form.
DVD
DVD (digital versatile disc) is an optical disc technology that is expected to rapidly
replace the CD-ROM disc (as well as the audio compact disc) over the next few years.
The digital versatile disc (DVD) holds 4.7 gigabyte of information on one of its two
sides, or enough for a 133-minute movie.
4.14 Classifying Memory/Storage
Electronic (RAM, ROM), magnetic (HD, FD, Tape), optical (CD, DVD)
Volatile (RAM), non-volatile (HD)
Direct access (RAM, HD), serial access (Tape)
Read/write (HD, RAM), read-only (CD)
4.15 Output Devices
Printer
Plotter
Speakers
Monitor
4.16 Modem
Modem is output as well as input device at the same time. It receives the data (analog
signal) coming through telephone line, converts them to digital signals and sends them to
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computer to which it is attached. It also receives the data from computer and changes it
to analog signals.
What have we learnt today?
What are the various types of computers with respect to their size, capability,
applications (FIVE TYPES)
The five essential components of any computer are input devices, processor, memory,
storage and output devices
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Lecture 5
Today’s goal is quite simple …
To learn about the various components of the popular personnel computer.
How those things are put together to form a PC
5.1 PC Parts
Monitor
Keyboard
Mouse
Speaker/headphone
Microphone
CPU
Front buttons
Backside ports, fan, slots, cables
5.2 Inside of the CPU
Power supply/fan & connectors
Motherboard
Bus
Edge connectors
Ports
Video card
Modem
Network card
Sound card
ROM
RAM
Slots
DIMM’s
5.3 The Processor Module
The slot on the motherboard
The housing
Fan
Heat sink
Pins (256?), Transistors (10 million?)
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Lecture 6
Learning Goals for Today
6.1 To develop your personal Web page
To upload your Web page to VU’s Web server so that it becomes visible on the Internet
as http://www.vu.edu.pk/~xxxxxxx/
where xxxxxxx is your user ID
http://www.vu.edu.pk/~altaf
HTML
Hyper Text Markup Language
<HTML>
<HEAD>
<TITLE>Altaf Khan's Home Page</TITLE>
</HEAD>
<BODY>
<H1>Altaf Khan</H1>
<P><B>Adjunct Lecturer in Computer Science</B><BR>
<A HREF="http://www.vu.edu.pk/">Virtual University</A><BR>
Building 1, 3rd Floor, Aiwan-e-Iqbal, Lahore<BR>
+92 42 555 1212<BR>
<A HREF="mailto:altaf@vu.edu.pk">altaf@vu.edu.pk</A><BR></P>
<P>I teach the <A HREF="http://www.vu.edu.pk/cs101/">Introduction to
Computing</A> course. </P>
</BODY>
</HTML>
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http://www.vu.edu.pk/~altaf/index.html
http://www.vu.edu.pk/~altaf
http://www.vu.edu.pk/~xxxxxxx
where xxxxxxx is your user ID
<HTML>
…
…
</HTML>
<HEAD>
…
…
</HEAD>
<TITLE> … </TITLE>
<BODY>
…
…
</BODY>
<P> … </P>
Paragraph
<BR>
Line break
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<B> … </B>
Bold text
<A HREF = “action” > label </A>
http://
example: “http://www.vu.edu.pk”
mailto:
example: “mailto:altaf@vu.edu.pk”
HTML Code
I am at the
<A HREF=“http://www.vu.edu.pk”>Virtual University</A>. You can send me an
e-mail by clicking
<A HREF=“mailto:bhola@vu.edu.pk”>here</A>.
Browser Display
I am at the Virtual University. You can send me an e-mail by clicking here.
What have we learned today?
We now know how Web pages are built using HTML
We also know how to make our personal Web pages available to everyone on the Internet
Useful URL’s
HTML for the Conceptually Challenged
http://www.arachnoid.com/lutusp/html_tutor.html
NCSA’s Beginner's Guide to HTML
http://archive.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimerAll.html
Homework Assignment
Develop your own home page. It should be accessible as
http://www.vu.edu.pk/~xxxxxxx (xxxxxxxx is your user ID)
Among other things, it should contain
At least one link to http://www.vu.edu.pk/~altaf
Your (clickable) email address
A paragraph (50-100 words) on what you see yourself doing 10 years from now.
Consult your syllabus for the submission deadline for this assignment
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Lecture 7
Goals for Today
Today we want to learn about the microprocessor, the key component, the brain, of a
computer
We’ll learn about the function of a microprocessor
And its various sub-systems
Bus interface unit
Data & instruction cache memory
Instruction decoder
Arithmetic-Logic unit
Floating-point unit
Control unit
7.1 Microprocessor
A microprocessor (abbreviated as μP or uP) is a computer processor on a microchip. It's
sometimes called a logic chip. A microprocessor is designed to perform arithmetic and
logic operations that make use of small number-holding areas called registers. Typical
microprocessor operations include adding, subtracting, comparing two numbers, and
fetching numbers from one area to another. These operations are the result of a set of
instructions that are part of the microprocessor design. When the computer is turned on,
the microprocessor is designed to get the first instruction from the basic input/output
system (BIOS) that comes with the computer as part of its memory. After that, either the
BIOS, or the operating system that BIOS loads into computer memory, or an
application program is "driving" the microprocessor, giving it instructions to perform.
The number of transistors available has a huge effect on the performance of a processor.
As seen earlier, a typical instruction in a processor like an 8088 took 15 clock cycles to
execute. Because of the design of the multiplier, it took approximately 80 cycles just to
do one 16-bit multiplication on the 8088. With more transistors, much more powerful
multipliers capable of single-cycle speeds become possible.
A microprocessor is made from miniaturized transistors and other circuit elements on a
silicon.
7.2 Integrated Circuits
A chip is also called an (integrated circuit (IC) (aka microchip or just chip). It is a
microelectronic semiconductor device consisting of many interconnected transistors and
other components.Generally it is a small, thin piece of silicon onto which the transistors
making up the microprocessor have been etched.
A chip might be as large as an inch on a side and can contain tens of millions of
transistors. Simpler processors might consist of a few thousand transistors etched onto a
chip just a few millimeters square. Integrated circuits can be classified into analog, digital
and mixed signal (both analog and digital on the same chip). Digital integrated circuits
can contain anything from one to millions of logic gates, flip-flops, multiplexers, etc. in a
few square millimeters. The small size of these circuits allows high speed, low power
dissipation, and reduced manufacturing cost compared with board-level integration.
The growth of complexity of integrated circuits follows a trend called "Moore's Law", it
states that the number of transistors in an integrated circuit doubles every two years.
7.3 Devices
7.3.1 Transistors
single semiconductor integrated circuit (IC) . These are made up of semiconductor and
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The transistor is a solid state semiconductor device used for amplification and
switching, and has three terminals. A small current or voltage applied to one terminal
controls the current through the other two, hence the term transistor; a voltage- or
current-controlled resistor. It is the key component in all modern electronics. In digital
circuits, transistors are used as very fast electrical switches, and arrangements of
transistors can function as logic gates, RAM-type memory and other devices. In analog
circuits, transistors are essentially used as amplifiers.
7.3.2 Diodes
A diode functions as the electronic version of a one-way valve. By restricting the
direction of movement of charge carriers, it allows an electric current to flow in one
direction, but blocks it in the opposite direction.
A diode's current-voltage, or I-V, characteristic can be approximated by two regions of
operation. Below a certain difference in potential between the two leads, the diode can
be thought of as an open (non-conductive) circuit. As the potential difference is
increased, at some stage the diode will become conductive and allow current to flow, at
which point it can be thought of as a connection with zero (or at least very low)
resistance. In a typical semiconductor p-n diode, conventional current can flow from the
p-doped side to the n-doped side, but not in the opposite direction. When the diode is
reverse-biased, the charge carriers are pulled away from the center of the device, creating
a depletion region. More specifically, the transfer function is logarithmic, but so sharp
that it looks like a corner.
7.3.3 Resistors
A resistor is an electrical component designed to have an electrical resistance that is
independent of the current flowing through it. The common type of resistor is also
designed to be independent of temperature and other factors. Resistors may be fixed or
variable. Variable resistors are also called potentiometers or rheostats
A few resistor types
Some resistors are long and thin, with the actual resisting material in the centre, and a
conducting metal leg on each end. This is called an axial package.
Resistors used in computers and other devices are typically much smaller, often in surfacemount
(Surface-mount technology) packages without leads.
Larger power resistors come in more sturdy packages designed to dissipate heat
efficiently, but they are all basically the same structure. Resistors are used as part of
electrical networks and incorporated into microelectronic semiconductor devices. The
critical measurement of a resistor is its resistance, which serves as a ratio of voltage to
current and is measured in ohms, an SI unit. Any physical object is a kind of resistor.
Most metals are conductors, and have low resistance to the flow of electricity. The
human body, a piece of plastic, or even a vacuum has a resistance that can be measured.
Materials that have very high resistance are called insulators.
7.3.4 Capacitors
A capacitor (historically known as a "condenser") is a device that stores energy in an
electric field, by accumulating an internal imbalance of electric charge. An ideal capacitor
can store electronic energy when disconnected from its charging circuit, so it can be used
like a fast battery. In AC or signal circuits it induces a phase difference of 90 degrees,
current leading potential.
They are connected in parallel with the power circuits of most electronic devices and
larger systems (such as factories) to shunt away and conceal current fluctuations from
the primary power source to provide a "clean" power supply for signal or control
circuits. The effect of such capacitors can be thought of in two different ways. One way
of thinking about it is that the capacitors act as a local reserve for the DC power source,
to smooth out fluctuations by charging and discharging each cycle. The other way to
think about it is that the capacitor and resistance of the power supply circuitry acts as a
filter and removes high frequencies, leaving only DC.
Wires
And are made of the following materials
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Silicon - semiconductor
Copper - conductor
Silicon Dioxide - insulator
7.4 Microprocessor system
Microprocessors are powerful pieces of hardware, but not much useful on their own.
They do not have the sense of their own. Like the human sample it needs some
instructions inputs and outputs to process some task. As per instruction given to the
microprocessor.
A microprocessor system is microprocessor plus all the components it requires to do a
certain task.
Shortly, a microprocessor needs help of some components to make up the task to fulfill.
These components are input, output, storage, and memory. All these components and
microprocessor make up a microprocessor system.
Personal Computer is an example of microprocessor System. Another example is the
microcontroller.
7.5 Micro-controllers
A microcontroller is a microprocessor optimised to be used to control electronic
equipment. Microcontrollers represent the vast majority of all computer chips sold, over
50% are "simple" controllers, and another 20% are more specialized decipline
processors. While you may have one or two general-purpose microprocessors in your
house (you're using one to read this), you likely have somewhere between one and two
dozen microcontrollers. They can be found in almost any electrical device, washing
machines, microwave ovens, telephones etc.
A microcontroller includes CPU, memory for the program (ROM), memory for data
(RAM), I/O lines to communicate with peripherals and complementary resources, all
this in a closed chip. A microcontroller differs from a standalone CPU, because the first
one generally is quite easy to make into a working computer, with a minimum of external
support chips. The idea is that the microcontroller will be placed in the device to control,
hooked up to power and any information it needs, and that's that.
7.6 The Main Memory Bottleneck
Modern super-fast microprocessors can process a huge amount of data in a short
duration. They need data to be processed at the same speed. Other wise they have to sit
idle and wait for the input/data, because speed of input is rather small then processing
of data. They require quick access to data to maximize their performance. If they don’t
receive the data that they require, they literally stop and wait, this results in reduced
performance and wasted power.
Current microprocessors can process an instruction in about ns (nanosecond). Time
required for fetching data from main memory (RAM) is of the order of 100 ns
Solution to the Bottleneck Problem
In order to eliminate the solution it was suggested to make the main memory faster. But
that evolved a problem that the 1-ns memory is extremely expensive as compared the
currently popular 100-ns memory.
Finally it was decided that in addition to the relatively slow main memory, put a small
amount of ultra-fast RAM right next to the microprocessor on the same chip and make
sure that frequently used data and instructions resides in that ultra-fast memory
It increases the performance. It supports better over performance due to fast access to
frequently used data and instructions.
7.7 Cache
A cache is a collection of duplicate data, where the original data is expensive to fetch or
compute (usually in terms of access time) relative to the cache. Future accesses to the
data can be made by accessing the cached copy rather than refetching or recomputing
the original data, so that the perceived average access time is lower. Caches may mark the
cached data as 'stale' when the original data is changed, but this is not always the case.
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On-Chip Cache Memory (1)
That small amount of memory located on the same chip as the microprocessor is called
On-Chip Cache Memory.
The microprocessor stores a copy of frequently used data and instructions in its cache
memory. When the microprocessor desires to look at a piece of data, it checks in the
cache first. If it is not there, only then the microprocessor asks for the same from the
main memory
On-Chip Cache Memory (2)
L2, cache memory, which is on a separate chip from the microprocessor but faster to
access than regular RAM.
It is the small size and proximity to the microprocessor makes access times short,
resulting in a boost in performance. Microprocessors predict what data will be required
for future calculations and it pre-fetches that data and places it in the cache so that it is
available immediately when the need arises.
7.8 Microprocessors Building Blocks
Bus Interface Unit
The bus interface unit is the part of the processor that interfaces with the rest of the PC.
Its name comes from the fact that it deals with moving information over the processor
data bus, the primary conduit for the transfer of information to and from the CPU. The
bus interface unit is responsible for responding to all signals that go to the processor,
and generating all signals that go from the processor to other parts of the system.
It receives instructions & data from main memory to be processed and operations. After
the operations are processed it then sends back the information (processed data) to the
cache. It also receives the processed data to send it to the main memory.
Instruction Decoder
The instruction decoder of a processor is a combinatorial circuit sometimes in the form of a
read-only memory, sometimes in the form of an ordinary combinatorial circuit. Its
purpose is to translate an instruction code into the address in the micro memory where
the micro code for the instruction starts.
Registers
Registers
Microprocessor
Instruction
Cache
Arithmetic
& Logic
Unit
Control
Bus Unit
Interface
Unit
Data
Cache
Instruction
Decoder
I/O
RAM
Memory
Bus
System
Bus
Floating
Point
Unit
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A decoder is a device which is the reverse, undoing the encoding so that the original
information can be retrieved. The same method used to encode is usually just reversed in
order to decode.This unit receives the programming instructions and decodes them into
a form that is understandable by the processing units, i.e. The ALU or FPU Then, it
passes on the decoded instruction to the ALU or FPUs as desired.
Arithmetic & Logic Unit (ALU)
An arithmetic and logical unit (ALU) also known as “Integer Unit” is one of the core
components of all central processing units. It is capable of calculating the results of a
wide variety of common computations. The most common available operations are the
integer arithmetic operations of addition, subtraction, and multiplication, the bitwise
logic operations of AND, NOT, OR, and XOR, and various shift operations.
The ALU takes as inputs the data to be operated on and a code from the control unit
indicating which operation to perform, and for output provides the result of the
computation. In some designs it may also take as input and output a set of condition
codes, which can be used to indicate cases such as carry-in or carry-out, overflow, or
other statuses.
The new breed of popular microprocessors have not one but two almost identical ALU’s
that can do calculations simultaneously, doubling the capability
Floating-Point Unit (FPU)
A floating point unit (FPU) is a part of a CPU specially designed to carry out
operations on floating point numbers. Typical operations are floating point arithmetic
(such as addition and multiplication), but some systems may be capable of performing
exponential or trigonometric calculations as well (such as square roots or cosines).
Not all CPUs have a dedicated FPU. In the absence of an FPU, the CPU may use a
microcode program to emulate an FPUs function using an arithmetic and logical unit
(ALU), which saves the added hardware cost of an FPU but is significantly slower.
In some computer architectures, floating point operations are handled completely
separate from integer operations, with dedicated floating point registers and independent
clocking schemes. Floating point addition and multiplication operations are typically
pipelined, but more complicated operations, like division, may not be, and some systems
may even have a dedicated floating point divider circuit.
Registers
A register is a device for storing data. It is a small amount of very fast computer
memory used to speed the execution of computer programs by providing quick access to
commonly used values. These registers are the top of the memory hierarchy, and are the
fastest way for the system to manipulate data. It is common to measure registers by the
number of bits it can hold, for example, an "8-bit register" or "32-bit register". Registers
are now usually implemented as an array of SRAMs, but they have also been
implemented using individual flip flops, high speed core memory, thin film memory, and
other ways in various machines.
There are several other classes of registers:
Data registers are used to store integer numbers.
Address registers hold memory addresses and are used to access memory.
General Purpose registers can store both data and addresses.
Floating Point registers are used to store floating point numbers.
Constant registers hold read-only values (e.g zero or one).
Vector registers hold data for Single Instruction Multiple Data (SIMD) instructions.
Special Purpose registers which store internal CPU data like the stack pointer or
processor status words.
The ALU & FPU store intermediate and final results from their calculations in these
registers. Then the processed data goes back to the data cache and then to main memory
from these registers.
Control Unit
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A control unit is the part of a CPU or other device that directs its operation. The
outputs of the unit control the activity of the rest of the device. A control unit can be
thought of as a finite state machine. It is called the brain of computer microprcessor. It
manages whole process of the microprocessor. For it identifes which data is sent to the
ALU or memory etc.
At one time control units for CPUs were ad-hoc logic, and they were difficult to design.
Now they are often implemented as a microprogram that is stored in a control store.
That was the structure, now let’s talk about the language of a microprocessor
Instruction Set
The set of machine instructions that a microprocessor recognizes and can execute – the
only language microprocessor knows
An instruction set includes low-level, a single step-at-a-time instructions, such as add,
subtract, multiply, and divide
Each microprocessor family has its unique instruction set
Bigger instruction-sets mean more complex chips (higher costs, reduced efficiency), but
shorter programs
An instruction set, or instruction set architecture (ISA), is a specification detailing the
commands that a computer's CPU should be able to understand and execute, or the set
of all commands implemented by a particular CPU design. The term describes the
aspects of a computer or microprocessor typically visible to a programmer, including the
native datatypes, instructions, registers, memory architecture, interrupt and fault system,
and external I/O (if any). "Instruction set architecture" is sometimes used to distinguish
this set of characteristics from the Micro-Architecture, which are the elements and
techniques used to implement the ISA, e.g. microcode, pipelining, cache systems, etc.
Bigger instruction-sets mean more complex chips (higher costs, reduced efficiency), but
shorter programs. Each microprocessor family has its unique instruction set. Following
are the few ISA;
MIPS
Motorola 6800
ARM
PowerPC
x86 (Pentium)
ALGOL Object Code
SPARC
7.9The 1st microprocessor : Intel 4004
The first microprocessor was the Intel 4004, introduced in 1971. The 4004 was not very
powerful all it could do was add and subtract, and it could only do that 4 bits at a time. But it
was amazing that everything was on one chip. Prior to the 4004, engineers built computers
Registers
Registers
Arithmetic
& Logic
Unit
Control
Bus Unit
Interface
Unit
Data
Cache
Instruction
Decoder
I/O
Memory
Bus
System
Bus Floating
Point
Unit
Instruction
Cache
Microprocessor
RAM
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either from collections of chips or from discrete components (transistors wired one at a
time). The 4004 powered one of the first portable electronic calculators. It was as powerful
as ENIAC which had 18000 tubes and occupied a large room. It cost less then $100. Its
targeted use was of calculation. It consisted of 2250 transistors and 16pins. Speed was 108
kHz, 60,000 ops/sec.
Why Intel came up with the idea?
A Japanese calculator manufacturer, Busicom wanted Intel to develop 16 separate IC’s
for a line of new calculators. Intel, at that point in time known only as a memory
manufacturer, was quite small and did not have the resources to do all 16 chips. Then
Ted Hoff came up with the idea of doing all 16 on a single chip. Later, Intel realized that
the 4004 could have other uses as well.
Currently Intel came with – Intel Pentium 4 (2.2GHz).
It was introduced in December 2001. It got 55 million transistors. 32-bit word size.
Within the processor it has 2 ALU’s each working at 4.4GHz. It costs around $600.
Moore’s Law
Moore's law(1965) is an empirical observation stating in effect that at our rate of
technological development and advances in the semiconductor industry the complexity
of integrated circuits doubles every 18 months. His original empirical observation was
that the number of components on semiconductor chips with lowest per-component
cost doubles roughly every 12 months, and he conjectured that the trend will stay for at
least 10 years. In 1975, Moore revised his estimate for the expected doubling time,
arguing that it was slowing down to about two years
4-, 8-, 16-, 32-, 64-bit (Word Length)
The 4004 dealt with data in chunks of 4-bits at a time
Pentium 4 deals with data in chunks (words) of 32-bit length
The new Itanium processor deals with 64-bit chunks (words) at a time
kHz, MHz, GHz (Clock Frequency)
4004 worked at a clock frequency of 108kHz
The latest processors have clock freqs. in GHz
Out of 2 microprocessors having similar designs, one with higher clock frequency will
be more powerful
Same is not true for 2 microprocessors of dissimilar designs. Example: Out of
PowerPC & Pentium 4 microprocessors working at the same freq, the former performs
better due to superior design. Same for the Athlon microprocessor when compared with
a Pentium
Enhancing the capability of a microprocessor ?
The computing capability of a microprocessor can be enhanced in many different
ways:
Evolution of Intel Microprocessors
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By increasing the clock frequency
By increasing the word-width
By having a more effective caching algorithm and the right cache size
By adding more functional units (e.g. ALU’s, FPU’s, Vector/SIMD units, etc.)
Improving the architecture
What have we learnt today?
Today we learnt about the microprocessor, the key component, the brain, of a computer
We learnt about the function of a microprocessor
And its various sub-systems
Bus interface unit
Data & instruction cache memory
Instruction decoder
ALU
Floating-point unit
Control unit
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Lecture 8
Binary Numbers & Logic Operations
The focus of the last lecture was on the microprocessor
During that lecture we learnt about the function of the central component of a
computer, the microprocessor
And its various sub-systems
Bus interface unit
Data & instruction cache memory
Instruction decoder
ALU
Floating-point unit
Control unit
Learning Goals for Today
To become familiar with number system used by the microprocessors - binary numbers
To become able to perform decimal-to-binary conversions
To understand the NOT, AND, OR and XOR logic operations – the fundamental
operations that are available in all microprocessors
BINARY
(BASE 2)
numbers
DECIMAL
(BASE 10)
numbers
Decimal (base 10) number system consists of 10 symbols or digits
0 1 2 3 4
5 6 7 8 9
Binary (base 2) number system consists of just two
0 1
Other popular number systems
Octal
base = 8
8 symbols (0,1,2,3,4,5,6,7)
Hexadecimal
base = 16
16 symbols (0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F)
Decimal (base 10) numbers are expressed in the
positional notation
4202 = 2x100 + 0x101 + 2x102 +
4x103
The right-most is the least significant
di i
The left-most is the most significant digit
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Decimal (base 10) numbers are expressed
in the positional notation
4202 = 2x100 + 0x101 + 2x102 + 4x103
1’s multiplier
1
Decimal (base 10) numbers are expressed
in the positional notation
4202 = 2x100 + 0x101 + 2x102 + 4x103
10’s multiplier
10
Decimal (base 10) numbers are expressed in
the positional notation
4202 = 2x100 + 0x101 + 2x102 + 4x103
100’s multiplier
100
Decimal (base 10) numbers are expressed in
the positional notation
4202 = 2x100 + 0x101 + 2x102 + 4x103
1000’s multiplier
1000
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Binary (base 2) numbers are also expressed in
the positional notation
10011=1x20+1x21+0x22+0x23+1x24
The right-most is the least significant
di i
The left-most is the most significant digit
Binary (base 2) numbers are also expressed
in the positional notation
10011=1x20+1x21+0x22+0x23+1x24
1’s multiplier
1
Binary (base 2) numbers are also expressed in
the positional notation
10011=1x20+1x21+0x22+0x23+1x24
8’s multiplier
8
Binary (base 2) numbers are also expressed in
the positional notation
10011=1x20+1x21+0x22+0x23+1x24
16’s multiplier
16
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8.1 Why binary
Because this system is natural for digital computers
The fundamental building block of a digital computer – the switch – possesses two
natural states, ON & OFF.
It is natural to represent those states in a number system that has only two symbols, 1
and 0, i.e. the binary number system
In some ways, the decimal number system is natural to us humans. Why?
bit
binary digit
Byte = 8 bits
Decimal Binary conversion
.
Check
1001011 = 1x20 + 1x21 + 0x22 + 1x23 + 0x24 + 0x25 + 1x26
= 1 + 2 + 0 + 8 + 0 + 0 + 64
= 75
Counting in
Decimal
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
.
.
.
01
10
11
100
101
110
111
1000
1001
1010
1011
1100
1101
1110
1111
10000
10001
10010
10011
10100
10101
10110
10111
11000
11001
11010
11011
11100
11101
11110
11111
100000
100001
100010
100011
100100
.
.
.
Counting in
Binary
Convert 75 to Binary
2 75
2 37 1
2 18 1
2 9 0
2 4 1
2 2 0
2 1 0
0 1
remainde
1001011
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That finishes our first topic - introduction to binary numbers and their conversion to
and from decimal numbers
Our next topic is …
8.2 Boolean Logic Operations
Let x, y, z be Boolean variables. Boolean variables can only have binary values i.e., they
can have values which are either 0 or 1.
For example, if we represent the state of a light switch with a Boolean variable x, we will
assign a value of 0 to x when the switch is OFF, and 1 when it is ON
A few other names for the states of these Boolean variables
0 1
Off On
Low High
False True
We define the following logic operations or functions among the Boolean
variables
Name Example Symbolically
NOT y = NOT(x) x´
AND z = x AND y x · y
OR z = x OR y x + y
XOR z = x XOR y x ⊕ y
Convert 100 to Binary
2 10
2 5 0
2 2 0
2 1 1
2 6 0
2 3 0
2 1 1
0 1
1100100
remainde
r
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We’ll define these operations with the help of truth tables
what is the truth table of a logic function
A truth table defines the output of a logic function for all possible inputs
Truth Table for the NOT Operation
(y true whenever x is false)
X y = x´
0
1
Truth Table for the NOT Operation
X y = x´
0 1
1 0
Truth Table for the AND Operation
(z true when both x & y true)
X y z = x · y
0 0
0 1
1 0
1 1
Truth Table for the AND Operation
X y z = x · y
0 0 0
0 1 0
1 0 0
1 1 1
Truth Table for the OR Operation
(z true when x or y or both true)
x y z = x + y
0 0
0 1
1 0
1 1
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Truth Table for the OR Operation
x y z = x + y
0 0 0
0 1 1
1 0 1
1 1 1
Truth Table for the XOR Operation
(z true when x or y true, but not both)
X y z = x ⊕ y
0 0
0 1
1 0
1 1
8.3 Truth Table for the XOR Operation
X y z = x ⊕ y
0 0 0
0 1 1
1 0 1
1 1 0
Those 4 were the fundamental logic operations. Here are examples of a few more
complex situations
z = (x + y)´
z = y · (x + y)
z = (y · x) ⊕ w
8.4 STRATEGY: Divide & Conquer
z = (x + y)´
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x y x + y z = (x + y)´
0 0 0 1
0 1 1 0
1 0 1 0
1 1 1 0
z = y · (x + y)
x y x + y z = y · (x
+ y)
0 0 0 0
0 1 1 1
1 0 1 0
1 1 1 1
z = (y · x) ⊕ w
x y W y · x z = (y · x)
⊕ w
0 0 0 0 0
0 0 1 0 1
0 1 0 0 0
0 1 1 0 1
1 0 0 0 0
1 0 1 0 1
1 1 0 1 1
1 1 1 1 0
Number of rows in a truth table?
2n
n = number of input variables
What have we learnt today?
About the binary number system, and how it differs from the decimal system
Positional notation for representing binary and decimal numbers
A process (or algorithm) which can be used to convert decimal numbers to binary
numbers
Basic logic operations for Boolean variables, i.e. NOT, OR, AND, XOR, NOR,
NAND, XNOR
Construction of truth tables (How many rows?)
Focus of the Next Lecture
Next lecture will be the 3rd on Web dev
The focus of the one after that, the 10th lecture, however, will be on software. During
that lecture we will try:
To understand the role of software in computing
To become able to differentiate between system and application software
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Lecture 9
HTML Lists & Tables
(Web Development Lecture 3)
Today is our 3rd Web Dev lecture During our 2nd lecture on Web dev …
We learnt to develop our own Web pages in HTML
We learnt about some of the tags used in HTML pages
<BR>, <P>, </P>, <B>, <TITLE>, </TITLE>, <H1>, </H1>
<HTML></HTML>, <HEAD></HEAD>, <BODY></BODY>
<A HREF = “action” > label </A>, action=http:// or mailto:
We also learnt about how to upload our Web pages to VU’s Web server so that it
becomes visible on the Internet as http://www.vu.edu.pk/~xxxxxxxx/
where xxxxxxxx is your VU user ID
Today’s Lecture
We will extend our Web pages by adding a few more tags
Specifically, we will learn about various types of lists that can be added to a Web page
And also, about tables
But first …
A few comments on the general structure of HTML tags
9.1 Single Tags
<tagName>
Example: <BR>
Single Tags with Atributes
<tagName attributes>
Example: <HR width=“50%”>
Paired Tags
<tagName> … </tagName>
Example: <H1> … </H1>
Paired Tags with Attributes
<tagName attributes > … </tagName>
Example: <H1 align=“center”> … </H1>
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List
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<HTML>
<HEAD>
<TITLE>Altaf Khan's Home Page</TITLE>
</HEAD>
<BODY>
<H1>Altaf Khan</H1>
<P><B>Adjunct Lecturer in Computer Science</B><BR>
<A HREF="http://www.vu.edu.pk/">Virtual University</A><BR>
Building 1, 3rd Floor, Aiwan-e-Iqbal, Lahore<BR>
+92 42 555 1212<BR>
<A HREF="mailto:altaf@vu.edu.pk">altaf@vu.edu.pk</A><BR></P>
<P>I teach the <A HREF="http://www.vu.edu.pk/cs101/">Introduction to
Computing</A> course. </P>
</BODY>
</HTML>
<HTML>
<HEAD>
<TITLE>Altaf Khan's Home Page</TITLE>
</HEAD>
<BODY>
<H1>Altaf Khan</H1>
<P><B>Adjunct Lecturer in Computer Science</B><BR>
<A HREF="http://www.vu.edu.pk/">Virtual University</A><BR>
Building 1, 3rd Floor, Aiwan-e-Iqbal, Lahore<BR>
+92 42 555 1212<BR>
<A HREF="mailto:altaf@vu.edu.pk">altaf@vu.edu.pk</A><BR></P>
<P>I teach the <A HREF="http://www.vu.edu.pk/cs101/">Introduction to
Computing</A> course. </P>
The additional code for the list and
table goes here
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</BODY>
</HTML>
<UL> Un-ordered List
<P>My favorite PC games are:</P>
<UL>
<LI>SimCity</LI>
<LI>Quake</LI>
<LI>Bridge</LI>
</UL>
<P>My favorite sports are:</P>
<TABLE border = “1” >
<TR>
<TH>Indoor</TH>
<TH>Outdoor</TH>
</TR>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
<P>My favorite PC games are:</P>
<UL>
<LI>SimCity</LI>
<LI>Quake</LI>
<LI>Bridge</LI>
</UL>
<P>My favorite sports are:</P>
<TABLE border = “1” >
<TR>
<TH>Indoor</TH>
<TH>Outdoor</TH>
</TR>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
Additional
code
Code for
the list
Code for
the table
HTML Code
<UL>
<LI>SimCity</LI>
<LI>Quake</LI>
<LI>Bridge</LI>
</UL> • SimCity
• Quake
• Bridge
Browser Display
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<LI> Line Item
The default “bullet” for these lists is a “disc”
That, however, can be changed to a “circle” or a “square” with the help of the type
attribute
HTML Code
<UL type = “circle”>
<LI>SimCity</LI>
<LI>Quake</LI>
<LI>Bridge</LI>
</UL>
• SimCity
• Quake
• Bridge
Browser Display
Q: What happens if I start a new list without
<UL> closing the original one?
<LI>SimCity</LI>
<LI>Quake II</LI>
<UL>
<LI>SimCity 3000</LI>
<LI>Quake III</LI>
</UL>
<LI>Bridge</LI>
</UL>
• SimCity
• Quake II
• SimCity
3000
• Quake
III
• Bridge
Browser Display
Different bullets
Additional tab
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Such structures, i.e., those in which another starts before the first list is finished, are
called Nested Lists
9.2 Types of Lists
In addition to un-ordered lists, HTML supports two other types
Ordered Lists
Definition List
9.3 Ordered List Types
Type Result
“A” A, B, C, …
“a” a, b, c, …
“I” I, II, III, IV, …
“i” i, ii, iii, iv, …
“1” 1, 2, 3, …
Ordered List
<OL>
<LI>SimCity</LI>
<LI>Quake</LI>
<LI>Bridge</LI>
</OL>
1. SimCity
2. Quake
3. Bridge
Browser Display
OL instead
of UL
Numbers instead
of discs, circles or
squares
Ordered List
<OL type = “a”>
<LI>SimCity</LI>
<LI>Quake</LI>
<LI>Bridge</LI>
</OL>
a. SimCity
b. Quake
c. Bridge
Browser Display
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<DL> Definition List
<DT> Term
<DD> Definition
Q: How would one start an ordered list with
something other than 1
25. SimCity
26. Quake
27. Bridge
Browser
Display
Ordered List
<OL start = “25”>
<LI>SimCity</LI>
<LI>Quake</LI>
<LI>Bridge</LI>
</OL>
25. SimCity
26. Quake
27. Bridge
Browser Display
Definition List
<DL>
<DT>SimCity</DT>
<DD>A great
simulation
game in
which one
build cities
</DD>
<DT>Quake</DT>
<DD> One of the
best of the
shoot-em-up
genre </DD>
</DL>
SimCity
A great
simulation
game in which
one build
cities
Quake
One of the
best of the
shoot-emup
genre
Browser
Display
Ter
Definition
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Ordered lists as well as definition lists can be nested just like the un-ordered lists
Can any type of list be nested into any other type?
Lists are one way of presenting data in a an ordered or formal fashion
Tables provide another - more customizable - way of displaying ordered information
on Web pages
<TABLE> Table
(made up of rows)
<TR> Row
(made up of data cells)
<TH>
Heading Data Cell
(Can contain paragraphs, images, lists,
forms, tables)
<TD>
Data Cell
(Can contain paragraphs, images, lists,
forms, tables)
<TABLE> Attributes
BORDER
Browser Display
Squash Cricket
Indoor Outdoor
HTML Code
<TABLE border = "1" >
<TR>
<TH>Indoor</TH>
<TH>Outdoor</TH>
</TR>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
Browser Display
Squash Cricket
Indoor Outdoor
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Determines the thickness of the table border
Example: <TABLE BORDER = “2”>
CELLPADING
Determines the distance between the border of a cell and the contents of the cell
Example: <TABLE CELLPADDING = “3”>
CELLSPACING
Determines the empty spacing between the borders of two adjacent cells
Example: <TABLE CELLSPACING = “1”>
<TABLE>,<TR>,<TH>,<TD> Attributes
ALIGN
Possible values: Center, Left, Right
Example: <TH ALIGN = “center”>
BGCOLOR
Example: <TD BGCOLOR = “red”>
WIDTH
HTML Code
<TABLE border = "1" >
<TR>
<TH>Indoor</TH>
<TH>Outdoor</TH>
</TR>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
HTML Code
Squash Cricket
Indoor Outdoor
HTML Code
<TABLE>
<TR>
<TH>Indoor</TH>
<TH>Outdoor</TH>
</TR>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
Browse Display
Indoor Outdoor
Squash Cricket
50% of
the
screen
width
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Example: <TR WIDTH = “40%”>
HEIGHT
Example: <TABLE HEIGHT = “200”>
<TR> Attributes
VLAIGN
Determines the vertical alignment of the contents of all of the cells in a particular row
Possible values: Top, Middle, Bottom
Example: <TR VALIGN = “bottom”>
<TH> & <TD> Attributes
NOWRAP
Extend the width of a cell, if necessary, to fit the contents of the cell in a single line
Example: <TD NOWRAP>
COLSPAN
No. of rows the current cell should extend itself downward
Example: <TD COLSPAN = “2”>
ROWSPAN
The number of columns the current cell should extend itself
Example: <TD ROWSPAN = “5”>
VALIGN
Same as that for <TR>
Expenses Income
Year Quarter
Quetta Dubai Quetta Dubai
1 1,900 8,650 9,000 7,780
2 2,230 8,650 8,500 8,670
2001
3 4,000 8,650 9,900 9,870
HTML CODE
<TABLE border=“1” >
<TR>
<TH colspan=“2”>
Indoor Outdoor
</TH>
</TR>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
Browse Display
Indoor Outdoor
Squash Cricket
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4 2,200 8,650 9,800 9,900
1 7,780 8,650 7,780 9,000
2 8,670 8,650 8,670 8,500
3 9,870 8,650 9,870 9,900
2002
4 9,900 8,650 9,900 9,800
Must be placed
immediately after
the<TABLE> tag
9.4 Useful URL
The Table Sampler
In Today’s Lecture …
We learnt how to extend our Web pages by adding a few more tags
HTMAL Code Browser Display
<TABLE border = "1" >
<CAPTION>
My favorite sports
</CAPTION>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
My favorite sports
Squash Sports
HTMAL Code
<TABLE border = "1" >
<CAPTION>
My favorite sports
</CAPTION>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
Browser Display
My favorite sports
Squash Sports
Must be placed
immediately after
the<TABLE> tag
http://hissa.nist.gov/~black/tableQuikRef.html
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Specifically, we discussed various types of lists that can be added to a Web page – unordered,
ordered and definition lists
And also, about tables: about various tags used in a table and their associated attributes
Next Web Dev Lecture:
Interactive Forms
We will try to understand the utility of forms on Web pages
We will find out about the various components that are used in a form
We will become able to build a simple, interactive form
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Lecture 10
Computer Software
Lecture 8 was on the binary number system and logic operations
Learning Goals for Today
To discuss the role of software in computing systems
To learn to differentiate among software belonging to the system and application
categories
To learn about software ownership
We mentioned in Lecture 4 that at the highest level, two things are required for
computing
Hardware: The physical equipment in a computing environment such as the computer
and its peripheral devices (printers, speakers...)
Software: The set of instructions that operates various parts of the hardware. Also
termed as “computer program”
Computer Software
The HW needs SW to be useful; the SW needs HW to be useful
When the user needs something done by the computer, he/she gives instructions in the
form of SW to computer HW
These instructions need to be written in a language that is readily understood by
computer uP
10.1 Machine Language
A system of codes directly understandable by a computer's CPU is termed this CPU's
native or machine language. Although machine code may seem similar to assembly language
they are in fact two different types of languages. Machine code is composed only of the
two binary digits 0 and 1.
Every CPU has its own machine language, although there is considerable overlap
between some. If CPU A understands the full language of CPU B it is said that A is
compatible with B. CPU B may not be compatible with CPU A, as A may know a few
codes that B does not.
10.2 Language Translators
Human programmers write programs in a language that is easy to understand for them.
They use language translators to convert that program into machine language. It
converts the human understandable code in uPs understandable code, i.e. a language that
is easy to understand for the uPs
10.3 Software Development
A software development process is a process used to develop computer software. It
may be an ad hoc process, devised by the team for one project, but the term often refers
to a standardised, documented methodology which has been used before on similar
projects or one which is used habitually within an organisation.
The SW development process involves many steps, and coding, that is typing the
instructions in a high-level language is only a small part of that process – taking-up only
around 15% of the effort
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10.4 Major Types of SW
System SW
System software is responsible for controlling, integrating, and managing the individual
hardware components of a computer system.
System software performs tasks like transferring data from memory to disk, or rendering
systems, device drivers, compilers, assemblers, linkers, and utilities.
Software libraries that perform generic functions also tend to be regarded as system
software. System software stored on non-volatile storage on integrated circuits is usually
termed firmware. These generally perform the background tasks in a computer. These
programs, many times, talk directly to the HW.
Application SW
Programs that generally interact with the user to perform work that is useful to the user.
These programs generally talk to the HW through the assistance of system SW.
10.5 System SW are programs that …
Control the overall operation of the computer
OS
Interact directly with HW
Device drivers
Perform system management & maintenance
Utilities
Are used to develop or maintain other programs
Language translators
10.6 Operating System
Concept&Feasibility
User Requirements
Developer Specs
Planning
Design
Implementation
The Software Development Process
Hardware
Operating System
Utility Language
Translator
Device Driver
Scientific
Apps.
Business
Apps.
Productivity
Apps.
Entertainment
Apps.
System software
Application software
text onto a display specific kinds of system software include loading programs, operating
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It performs its work invisibly to control the internal functions of a computer, e.g.
maintaining files on the disk drive, managing the screen, controlling which tasks the uP
performs and in what order. It interacts directly with the computer HW. Other SW
normally does not directly interact with the HW, e.g.
Windows Mac OS Linux
UNIX Solaris DOS
CP/M VMS Firmware
ROM is a component of OS that permanently stored on a chip. It is a firm ware
program. When a computer is powered-on, it is the first program that it always executes.
Firmware consists of startup and a few low-level I/O routines that assist the computer
in finding out and executing the rest of the OS. On IBM-compatible PC’s, it is called
BIOS
10.7 Utilities:
It is a small program that provides an addition to the capabilities provided by the
operating system. In some usages, a utility is a special and nonessential part of the
operating system. These are the computer programs that perform a particular function
related to computer system management and maintenance
Examples:
1. Anti-virus SW
2. Data compression SW
Disk optimization SW
Disk backup SW
10.8 Language Translators
Programs that take code written in a HLL and translate it into a low-level language that
is easily understood by the uP
1. Compiler translates the program written in a HLL in one go. The translated code is
then used by the uP whenever the program needs to be run
2. Interpreter translates the HLL program one statement at time. It reads a single
statement, translates it into machine language and passes that machine language code to
the uP and then translates the next statement, and so on …
10.9 Device Drivers
A device driver, often called a driver for short, is a computer program that is intended
to allow another program (typically, an operating system) to interact with a hardware
device. Think of a driver as a manual that gives the operating system (e.g., Windows)
instructions on how to use a particular piece of hardware.
A device driver essentially converts the more general input/output instructions of the
operating system to messages that the device type can understand.
10.10 Application SW
Application SW are programs that interact directly with the user for the performance of
a certain type of work
Scientific/engineering/graphics SW
Mathematica; AutoCad; Corel Draw
Business SW
The billing system for the mobile phone company
Productivity SW
Word processors; Spreadsheets
Entertainment SW
Games
Educational SW
Electronic encyclopedias; The VU Web site
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10.11 Another way of classifying SW
Shrink-Wrapped SW
You can just go to a shop and buy it
Custom-built SW
You cannot just go to a shop and buy it; you have to find someone who can develop it
for you
Shrink-Wrapped SW
SW built in such a way that it is useful for many different users in many different ways.
Example: MS Word. Individuals use it and so do many large corporations. It is used
for writing one-page letters and also to typeset books
Custom-Built SW (1)
These SW are built for a particular organization to fulfill the needs of that particular
organization. This type of SW is expensive because the builder has to recoup costs and
make a profit from a single sale
Example: A system for predicting the preferences of the Nortwest Airline pilots
Custom-Built SW (2)
This is other type of custom built SW. The delivery time is longer. Customers get more
productivity out of it because it is built according to their exact specifications – just like a
custom-built shoe fits better, but generally is more expensive, and requires a longer
period for delivery
10.12 Who Owns Software?
Generally, although a piece of SW that is being used by millions, it is not owned by any
of them! Instead, it is owned by the maker of the SW
The makers let us use their SW but keep the ownership to themselves. When we buy a
SW package, we do not really buy it – we just buy a license that allows us to use it, the
ownership stays with the maker
However, there are variations on this theme …
10.13 Main types of SW licensees
Proprietary – Most software on a Windows PC or a Macintosh belongs to this category
Freeware – Most software on a Linux PC belongs to that category
Shareware – the category which lies between the above two categories
10.14 Proprietary SW License
Proprietary software, as defined by the Free Software Foundation, means any software
that is not free software or is only partially free. The modification, use and redistribution
Hardware
Operating System
Utility Language
Translator
Device Driver
Scientific
Apps.
Business
Apps.
Productivity
Apps.
Entertainment
Apps.
System software
Application software
are prohibited, or requires express permissions from the originator. The user needs to
pay the maker of the SW for buying a license that allows the user to use the SW
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The license, generally, does not transfer the ownership of the SW; it just allows the user
to use it. The user is legally barred from making copies of the licensed SW. Generally,
the license is for the personal use only. Most SW in use in the world is of this type.
Examples: Windows, Mac OS, MS Word, Adobe Photoshop, Norton Antivirus
Types of Proprietary Licenses
Single-user license
Multi-user license
Concurrent-user license
Site license
10.15 Freeware SW License
It is also known as “Public Domain SW”. It allows the user to free use of the SW. The
author, however, generally retains ownership. It can usually be downloaded from various
Web sites.
Examples: Linux; LaTeX; Netscape Web browser – the Navigator; MS Web browser –
the Internet Explorer
10.16 Open-Source SW License
Some authors give away the machine code only, which is extremely difficult to modify, if
at all. Others even give away the high-level language source code so that users can make
changes according to their own requirements. The later practice is called open-source
licensing.
Generally is any computer software whose source code is either in the public domain or,
more commonly, is copyrighted by one or more persons/entities and distributed under
an open-source license . Such a license may require that the source code be distributed
along with the software, and that the source code be freely modifiable, with at most
minor restrictions, such as a requirement to preserve the authors' names and copyright
statement in the code,
Examples: Linux; Netscape Navigator
10.17 Shareware SW License
Shareware is software that is distributed without payment ahead of time as is common
for proprietary software. Typically shareware software is obtained free of charge by
downloading, thus allowing one to try out the program ahead of time. A shareware
program is accompanied by a request for payment, and often payment is required per the
terms of the license past a set period of time. shareware are similar in that they can be
obtained and used without monetary cost. Usually shareware differs from open source
software in that requests of voluntary "shareware fees" are made, often within the
program itself, and in that source code for shareware programs is generally not available
in a form that would allow others to extend the program.
A shareware's program source, maintenance and extensibililty can sometimes be
negotiated for a licensing fee with the author(s) similar to standard proprietary software.
Examples: WinZip, Download Accelerator
10.18 Trialware
It is similar to shareware but difference is that the SW is usable for a short period only.
When the period is expired, it is no more in use until the license is not purchased. The
trial period may vary according to its developer. This period may range from a week to a
few months.
It can be downloaded from the Internet or alternatively.
What have we learnt today?
We have found out about the role software plays in a computing environment
We also learned to distinguish between software belonging to the system and application
categories
We also discussed the different types of software licenses
Topics of some of the future lectures
Operating system
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Application SW
Productivity SW
Word processor
Spreadsheets
Presentation making
Databases
Programming Languages
The SW development process
The Web development series of lectures is clearly focused on developing SW
Focus of the Next Lecture
The role of the OS in a computing environment
The various functions that an OS performs
The main components of an OS
Various types of OSes
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Lecture 11
Operating Systems
Focus of the last lecture: computer SW
We found out about the role SW plays in a computing environment
We learned to distinguish between SW belonging to the system & application categories
Also discussed the different types of SW licenses:
Proprietary
Free
Open source
Shareware
Trialware
Learning Goals for Today
The role of the operating system in a computing environment
The various functions that an operating system performs
The main components of an operating system
Various types of operating systems
11.1 Why Have OSes?
User/programmer convenience
Greater resource utilization
The Role of An OS
The 1st program that runs when a typical computer is turned ON, and the last one to
finish running when the computer is turned OFF.
It manages the HW and SW resources of the computer system, often invisibly. These
include the processor, memory, disk drives, etc.
It provides a simple, consistent way for applications to interact with the HW without
having to know all the details of the HW
Advantage for App. Developers
Application developers do not need to know much about the HW while they are
developing their app
They just develop with a particular OS in mind. If the OS runs on many types of
computers having different HW configurations, so will the app – without making any
HW-specific modifications in the app SW. The OS hides the HW differences from the
app
Are OS’es Essential?
No. If a computer has been designed for limited functionality (e.g. it runs just a single
program all the time as in a automatic clothes washing machine), it does not require a
traditional OS
In limited-functionality computers, an OS just adds to the overhead unnecessarily, which
impedes the computer’s performance
that is going to run
In the beginning …
A single user ran a single program ran on a single computer – there was no need for an
OS
Then came computer operators who ran multiple programs for multiple users one after
the other – still, no need for an OS
simultaneously. That’s when the need for OS’es arose for:
Managing the resources of the computers efficiently
Making use of computers convenient for users/programmers
11.2 Core Tasks of an OS
Processor management
Memory management
Device management
Storage management
In these situations, the required parts of the OS are integrated into the only program
Later computers became powerful and able to run multiple programs,
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Application Interface
User Interface
Processor Management
Memory Management
Straight forward for a single-user, single tasking
Each app must have enough private memory in which to execute
App can neither run into the private memory space of another app, nor be run into by
another app
Different types of memory (e.g. main, cache) in the system must be used properly, so
that each app can run most effectively
Storage Management
The OS manages storage through one of its sub-modules, the File Manager
A file system is a collection of directories, subdirectories, and files organized in a logical
order.
File manager maintains an index of the filenames & where they are located on the disk.
File manager make it easy to find the required file in a logical and timely fashion.
Device Management
Applications talk to devices through the OS and OS talks to and manages devices
through Device Drivers
Example: When we print to a laser printer, we do not need to know its details. All we
do is to tell the printer device driver about what needs to be printed and it takes care of
the details
Application Interface
App developers do not need to know much about the HW, especially the uP, while they
are developing their app
The OS provides all apps with a straight-forward and consistent interface to the HW
Example: An app uses the OS to store data on the disk drive. For that, the app does not
need to know about the exact physical characteristics of that drive; it just tells the OS to
do that through the app interface, and the OS takes cares of all the details of the task
User Interface
Users communicate with the computer using a consistent user interface provided by the
OS
This UI can be a command-line interface in which a user types in the commands.
Example:
copy a:/file1.html c:/file1.html
Or, it can be a graphical UI, where Windows, Icons, Menus, and a Pointing device (such
as a mouse) is used to receive and display information. Example:
With the help of the mouse, drag file1.html from drive a to drive c
11.3 OS Components
Error!
Kernel
Command
Interpreter
(Shell)
File
Manager
Device
Manager
GUI
Loader
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11.4 Kernel
The heart of the OS
Responsible for all the essential operations like basic house keeping, task scheduling, etc.
Also contains low-level HW interfaces
Size important, as it is memory-resident
11.5Types of OS’es
Classification w.r.t. the type of computers they run on and the type of applications they
support
Real-Time Operating System (RTOS)
Single-User, Single Task
Single-User, Multi-Tasking
Multi-User
RTOS (1)
Used to run computers embedded in machinery, robots, scientific instruments and
industrial systems
Typically, it has little user interaction capability, and no end-user utilities, since the
system will be a "sealed box" when delivered for use
Examples: Wind River, QNX, Real-time Linux, Real-time Windows NT
RTOS (2)
An important part of an RTOS is managing the resources of the computer so that a
particular operation executes in precisely the same amount of time every time it occurs
In a complex machine, having a part move more quickly just because system resources
are available may be just as catastrophic as having it not move at all because the system
was busy
Single-User, Single Task
OS’es designed to manage the computer so that one user can effectively do one thing at
a time
The Palm OS used in many palmtop computers (PDA’s) is an example of a single-user,
single-task OS
Single-User, Multi-Tasking
Most popular OS
Used by most all PC’s and Laptops
Examples: Windows, Mac OS, Linux
Lets a single user interact with several programs, simultaneously
Multi-User
A multi-user OS allows many users to take advantage of the computer's resources,
simultaneously
The OS must make sure that the requirements of the various users are balanced, and that
the programs they are using each have sufficient and separate resources so that a
problem with one user doesn't affect any of the other users
Examples: Linux, Unix, VMS and mainframe OS’es, such as MVS
11.6 Another Way of Classifying
Uni-processor OS’es
Designed to schedule tasks on a single uP only
Example: DOS
Multi-processor OS’es
Can control computers having multiple uPs, at times 1000’s of them
Example: Current versions of Windows, Mac OS, Linux,
Solaris
11.7 How many different OS’es are there?
100’s
OS’es from the Windows family dominate the desktops and run on millions of PC’s
OS’es from the Unix family (Unix, Linux, etc) are quite popular on servers
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There are hundreds more. Some designed for mainframes only. Some for embedded
applications only.
11.8 Comparing Popular OS’es
OS HW Stability Cost Apps. Support Security Popularity
Windows
(GUI) PC Poor $300 Huge
no. OK Poor Amazing
Mac OS
(Shell/GUI) Mac Good $60 Many OK Good Low
Linux
(Shell/GUI) Many Good Low Many Variable Good Low
Unix
(Shell/GUI) Many Excellent High Many Expensive Excellent Servers
What have we learnt today?
The role of the OS in a computing environment
The various functions that an OS performs
The main components of an OS
Various types of OS’es
Next Lecture: Application SW
We’ll learn about application SW, i.e. programs that interact directly with the user for the
performance of a certain type of work
We’ll try to become familiar with various SW used in the following application areas:
Scientific/engineering/graphics
Business
Productivity
Entertainment
Educational
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Lecture 12
Interactive Forms
(Web Development Lecture 4)
Focus of the last lecture was on HTML Lists & Tables
We learnt how to extend our Web pages by adding a few more tags
Specifically, we discussed various types of lists that can be added to a Web page – unordered,
ordered and definition lists
And also, about tables: about various tags used in a table and their associated attributes
Today’s Lecture
We will try to understand the utility of forms on Web pages
We will find out about the various components that are used in a form
We will become able to build a simple, interactive form
Interactive Forms (1)
Without forms, a Web site is “read-only” – it just provides information to the user
Forms enable the user to provide information to the Web site. For example, the user
can:
Perform searches on Web site
Give comments
Ask for info that is not available on the Website
Place order for goods and services
Interactive Forms (2)
Can be simple or very complex
Can fill a whole page or just a single line
Can contain a single element or many
Are always placed between the <BODY> and </BODY> tags of a Web page
Interactive Forms (3)
Are GUI-based
May contain:
Text fields
Check boxes
Buttons
Scrollable lists
Code for that Example
<HTML>
<HEAD>
<TITLE>Send Email to me</TITLE>
</HEAD>
A Simple
Example
of
Interactive
Forms
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<BODY>
<H1>Send Email to me</H1>
Code for the instructions
Code for the form
</BODY>
</HTML>
Code for the Instructions
<P>To send an eMail message to me:</P>
<OL>
<LI>Type your eMail address in the "From" field</LI>
<LI>Type a short message in the "Message" field</LI>
<LI>Press the "Send eMail to me" button</LI>
</OL>
Code for the Form
<FORM name="sendEmail" method="post" action="sendMailScriptURL">
Elements of the form
</FORM>
A Simple
Example
of
Interactive
Forms
A Simple
Example
of
Interactive
Forms
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12.1 Server-Side Scripts
Receive info that a user enters in a form
Process that info and take appropriate action
Examples:
CGI scripts on Unix servers
ASP scripts on Windows servers
Elements of the Form (1)
<P>From: <INPUT type="text" name=“sender" size="50"></P>
<P>Message: <INPUT type="text" name="message" size="50"></P>
<FORM name="sendEmail" method="post"
action="sendMailScriptURL">
Elements of the form
</FORM>
A Simple
Example
of
Interactive
Forms
name: Name given to the form
method: Forms can be submitted through two
alternate methods – GET & POST
when the form is being submitted
action: Specifies the URL that is accessed
Are programs that reside on Web servers
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Elements of the Form (2)
<P><INPUT type="hidden" name="receiver" value="altaf@vu.edu.pk"></P>
<P><INPUT type="hidden" name=“subject” value=“eMail from the form”></P>
<P><INPUT type="submit“ name="sendEmail" value="Send eMail to me"></P>
A Simple
Example
of
Interactive
Forms
A Simple
Example
of
Interactive
Forms
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<TEXTAREA
name=“message”
cols=“38”
rows=“6”
>
</TEXTAREA>
<FORM name="sendEmail" method="post" action=“sendMailScriptURL">
<table><tr>
<td>From: </td>
<td><INPUT type="text" name="sender" size="50"></td>
</tr><tr>
<td>To: </td>
<td><INPUT type="text" name="receiver" size="50"></td>
</tr><tr>
<td>Subject: </td>
<td><INPUT type="text" name="subject" size="50"></td>
</tr><tr>
<td valign="top">Message: </td>
<td><TEXTAREA name="message" cols="38"rows="6">
</TEXTAREA></td>
</tr><tr>
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<td colspan="2" align="right">
<INPUT type="submit" name="sendEmail" value="Send eMail">
</td>
</tr></table>
</FORM>
<INPUT
type=“text” name=“sender”
size=“50”
value=“your eMail address goes here”
Review of the Tags Used in Forms
<FORM>
name=“nameOfTheForm”
method=“get” or “post”
action=“URL”
Elements of the form
</FORM>
Single-Line Text Input Field
<INPUT
type=“text”
name=“fieldName”
size=“widthInCharacters”
maxlength=“limitInCharacters”
value=“initialDefaultValue”
>
Hidden Input
<INPUT
type=“hidden”
name=“fieldName”
value=“value”
>
Submit Button Input
<INPUT
type=“submit”
name=“buttonName”
value=“displayedText”
>
Multi-Line Text Input Area
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<TEXTAREA
name=“areaName”
cols=“widthInCharacters”
rows=“numberOfLines”
>
initial default value
</TEXTAREA>
This was a review of the new tags (and associated attributes) that we have used in today’s
examples. There are many more tags that can be used in a form.
Let us take a look at a few
<form name="login" method="post" action="loginScript">
<table><tr>
<td>User Name: </td>
<td>
<input type="text" name="userName" size="10">
</td>
</tr><tr>
<td>Password: </td>
<td>
<input type="password" name="password" size="10">
</td>
</tr><tr>
<td colspan="2" align="right">
<input type="submit" name="login" value="Log me in">
</td>
</tr></table>
</form>
Password Input Field
<INPUT
type=“password”
name=“fieldName”
size=“widthInCharacters”
maxlength=“limitInCharacters”
value=“initialDefaultValue”
>
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<form name="login" method="post" action="loginScript">
<table><tr>
<td>User Name: </td>
<td>
<input type="text" name="userName" size="10">
</td>
</tr><tr>
<td>Password: </td>
<td>
<input type="password" name="password" size="10">
</td>
</tr><tr>
<td colspan="2">
<input type="checkbox" name="remember" value="remember">
Remember my user name and password<br>
</td>
</tr><tr>
<td colspan="2">
<input type="submit" name="login" value="Log me in">
</td>
</tr></table>
</form>
12.2 Checkbox Input Element
<INPUT
type=“checkbox”
name=“checkboxName”
checked
value=“checkedValue”
>
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<form name="login" method="post" action="loginScript">
<table><tr>
<td>User Name: </td>
<td>
<input type="text" name="userName" size="10">
</td>
</tr><tr>
<td>Password: </td>
<td>
<input type="password" name="password" size="10">
</td>
</tr><tr>
<td valign="top">Logging in from:</td>
<td>
<input type="radio" name="from" value="home"> Home<br>
<input type="radio" name="from" value="office"> Home<br>
<input type="radio" name="from" value="university" checked> University
</td>
</tr><tr>
<td colspan="2" align="right">
<input type="submit" name="login" value="Log me in">
</td>
</tr></table>
</form>
12.3 Radio Button Input Element
<INPUT
type=“radio”
name=“radioButtonName”
checked
value=“selectedValue”
>
What is the difference between checkboxes and radio buttons?
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<form name="login" method="post" action="loginScript">
<table><tr>
<td>User Name: </td>
<td><input type="text" name="userName" size="10"></td>
</tr><tr>
<td>Password: </td>
<td>
<input type="password" name="password" size="10">
</td>
</tr><tr>
<td valign="top">Logging in from:</td>
<td>
<select size="2" name="from">
</select>
</td>
</tr><tr>
<td colspan="2">
<input type="submit" name="login" value="Log me in">
</td>
</tr></table>
</form>
12.4 Select from a (Drop Down) List
<SELECT
name=“listName”
size=“numberOfDisplayedChoices”
multiple
>
…
…
</SELECT>
<option value="university" selected> University </option>
<option value="office"> Office </option>
<option value="home"> Home</option>
<OPTION value=“value1”> text1 </OPTION>
<OPTION value=“value2” selected> text2 </OPTION>
<OPTION value=“value3”> text2 </OPTION>
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12.5 File Upload Input Element
<INPUT
type=“file”
name=“buttonName”
value=“nameOfSelectedFile”
enctype=“fileEncodingType”
>
<form
name=“uploadForm”
method=“post”
action=“uploadScript”
<input
type=“file”
name=“uploadFile”
enctype=“multipart/form-data”
>
<input
type=“submit”
name=“submit”
value=“Upload”
>
</form>
Reset Button Input Element
(Resets the contents of a form to default values)
<INPUT
type=“reset”
value=“dispalyedText”
>
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Today’s Lecture was the …
We looked at the utility of forms on Web pages
We found out about the various components that are used in a form
We became able to build a simple, interactive form
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Lecture 13
Application Software
The focus of the last lecture was on Operating Systems
Learning Goals for Today
To learn about application software
To become familiar with various software used in the following application areas:
e.g.
Scientific/engineering/graphics
Business
Productivity
Entertainment
Educational
13.1 Two Major Types of Software
System Software
Application Software
13.2 Application Software
Application software are programs that interact directly with the user
They generally do not talk directly to the hardware
13.3 Classification According to the Mode
Interactive-mode
The user runs the program on the computer and keeps on interacting with the computer
while the program runs
Example: Word processor
Batch-mode
The user starts the program and the computer processes the provided data and produces
results without any further intervention of from the user
Example: Payroll
13.4 Classification According to Application Area
Scientific/engineering/graphics
Business
Productivity
Entertainment
Educational
13.5 Scientific/Engineering/Graphics Apps
Key feature: Intense floating-point calculations
Scientific/engineering/mathematical apps
Computers initially were designed just to run them
Hardware
Operating System
Utility Language
Translator
Device Driver
Scientific
Apps.
Business
Apps.
Productivity
Apps.
Entertainment
Apps.
System software
Application software
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Generally designed for specialists
Rudimentary UI’s
Many run in batch mode
13.6 Scientific SW
Simulation of natural systems
Deforestation and effect on green-house gases
Simulation of artificial systems
NeuralWare (Simulator for artificial neural networks)
Thermo-nuclear explosions
Mathematical computation packages
Mathematica (can do hundreds, if not thousands of functions, e.g. solving a differential
eq, symbolically)
MathCAD
13.7 Engineering SW
Computer-aided design (CAD)
AutoCAD
SPICE
Virtual wind tunnels
Computer-aided manufacturing (CAM)
Telecommunication system SW
Centrex
Industrial control SW
13.8 Graphics & Animation SW (1)
Two types:
1. Vector graphics
Treats everything that is drawn as an object
Objects retain their identity after they are drawn
These objects can later be easily moved, stretched, duplicated, deleted, etc
Are resolution independent
Relatively small file size
Example: MS Visio, Corel Draw, Flash
Graphics & Animation SW (2)
2. Bit-mapped or raster graphics
Treats everything that is drawn as a bit-map
If an object is drawn on top of another, it is difficult to move just 1 of them while
leaving the other untouched
Changing the resolution often requires considerable touch-up work
Relatively large file size
Example: MS Paint, Adobe Photoshop
13.9 Business Applications
Most of the SW being developed today belongs to this category
SW that is required to run most any sort of biz:
Payroll
General ledger
Order entry
Accounts receivable & accounts payable
Inventory control
Let’s now discuss a few business SW categories which are not that common, but are
becoming more and more popular with time
13.10 E-Commerce Software
Key requirements:
Reliability
Security
Moving
graphics
e.g. cartoons
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Ability to handle 1000’s of transactions, simultaneously
13.11 ERP (Enterprise Resource Planning) SW
Very large scale, complex & expensive SW
Ties together all key activities & major systems of an organization into a single SW
system
Key benefit: Optimization of the business processes of an organization as a single system
instead of many loosely-related stand-alone systems
Example: SAP, Oracle, PeopleSoft, Baan
13.12 DSS (Decision Support Systems) SW
Sometimes also called “expert systems”
Many times are based on a branch of computer science called “artificial intelligence”
This category of SW is designed to help business managers in making effective decisions
in complex situations based on the analysis of the relevant data
13.13 Productivity SW
Most popular category in terms of licenses sold
Common features
Ability to simplify, automate everyday business tasks
Highly interactive and user-friendly design
Designed to run on PC’s
Most users do not use 90% of the SW features
Popular productivity SW
Word Processing -- Spreadsheets
Presentations -- Databases
13.14 Word Processors
Probably the most popular productivity app
Initially designed as a replacement for the typewriter
Automation
Automatic end-of-line soft carriage return
Style sheets
Table of contents & index
Spelling & grammar checking
Two approaches: WYSIWYG (e.g. Word, WordPerfect, Star) or traditional markup
(LaTeX)?
Desktop publishing
13.15 Web Page Development SW
Web pages can be developed using a simple plain-text editor like the “notepad”, but
more efficient, easy-to-use HTML editors can make the process quicker
Some of them are WYSIWYG (i.e. you don’t really need to know any HTML to use
them), others are not, while some provide both types of interfaces (DreamWeaver)
Most popular word processors now come with a built-in Web page development facility
13.16 Spreadsheet SW (1)
Electronic replacement for ledgers
Is used for automating engineering, scientific, but in majority of cases, business
calculations
A spreadsheet - VisiCalc - was the first popular application on PC’s.
It helped in popularizing PC’s by making the task of financial-forecasting much simpler,
allowing individuals to do forecasts which previously were performed by a whole team
of financial wizard
13.17 Spreadsheet SW (2)
Consist of cells arranged in rows and columns
Each cell may contain numeric values, text or formulas
Automation
Recalculations
Charts
13.18 Presentation Development SW
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Used to prepare multimedia material for lectures & presentations to display key points,
graphics, animation, or video with the help of multimedia projectors
Have replaced acetate films (slides) that were used with over-head projectors
Key advantage over acetate slides:
Easy to modify
Can be sent electronically
Its multimedia nature makes it more interesting for the audience
13.19 Small-Scale Databases SW (1)
Easy to use applications designed for efficient storage and fast and easy retrieval of data
That data may be in the form of numbers, text, or even multimedia, i.e. sounds, graphics,
animation, video
13.20 Small-Scale Databases SW (2)
Before the advent of the currently popular “relational” database model, the databasing
function was performed using what is called the “flat-file” model
That model is not very efficient for storing and searching in large databases
A database consists of a file or a set of files. Information in these is stored in the form
of records, and the records are further subdivided into fields
13.21 Productivity SW Suites
A set of stand-alone productivity applications designed to work easily with each other
Share a common UI
Are available as a bundle along with additional useful utilities
Examples: MS Office, Corel WordPerfect Office, Lotus SmartSuite, Star Office
SW Suites for other app areas are available as well, e.g. the Adobe suite of graphics apps
13.22 Document-Centered Computing (DCC) - 1
The increasing cooperation among the apps included in productivity suites has given rise
to a new computing paradigm called DCC
DCC implies that instead of developing parts of a doc in a number of apps, and then
cutting-&-pasting them to form the final doc, you stay in a single doc and call-up
appropriate apps to insert the required objects
13.23 Document-Centered Computing (DCC) - 2
Let’s say that we want to write a letter containing a map, a table and a graph
We can:
Launch the WP and type the text in
Insert a drawing by calling up the drawing toolbar app (without leaving the WP) & draw
the map
Insert a table by calling up the spreadsheet app (without leaving the WP) & build the
table
Insert a graph based on that table using the same spreadsheet app without leaving the
WP
13.24 Entertainment SW
Key feature: Simple, intuitive, many times social UI’s
The user is generally assumed to know nothing about computers
Both Microsoft & Apple are pursuing a PC-as-a-personal-entertainment-hub strategy.
Probable result: Already popular entertainment SW will become even more popular
13.25 Music & Video Players
Music players (WinAmp)
Video/Music players (Real player, Windows Media player, QuickTime player)
The Web Browsers can also display video, animation, and play music with the help of
helper applications like Flash
13.26 Music Generation & Movie Editing SW
A PC can be made the hub of a music making studio with help of appropriate HW &
SW
Inexpensive, easy-to-use video editing SW has recently become available for the iMac
13.27 Games
Many types
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Educational (especially for toddlers)
Strategy/Simulation
Sports
Shoot’em ups
The saddest aspect: You do not need any opponents or partners to play computer
games
The application SW category that provides the toughest challenge for computer HW
13.28 Educational SW
Category with probably the highest growth rate
Current focus on augmenting traditional training and education methods, but it is
shifting towards replacing traditional methods
13.29 Electronic Encyclopedias
Great resource of useful information presented in a very interesting format
Superior to the paper-based version because:
Access speed is dramatically higher
Can contain animation and sound
Much lower cost as thousand’s of pages in dozens of volumes have been replaced by a
couple of CD’s
13.30 On-Line Learning
With time, the VU Web site will become more and more focused on interactive online
learning
The Website of our textbook “Understanding Computers” is an example of an on-line
learning Website
Key features of good online learning SW:
The student can learns at his or her own pace
The student can select his or her own hours
13.31 Interactive CD’s
Same as on-line learning, but through a CD instead of a Web site
Key advantage:
Ideal for students with slow Internet access
13.32 Attributes of Good Application Software
Easy to install, un-install
User Interface
Consistent
Intuitive
Configurable
Adapts to the users need
Has a tutorial and a complete help manual
Does not have any critical bugs
13.33 Most Popular Application Software Categories
Web browsers
Email clients
Word processors
What have we learnt today?
Application software are programs that interact directly with the user for the
performance of a certain type of work
That work generally falls into one of the following usage areas
Scientific/engineering/graphics
Business
Productivity
Entertainment
Educational
Focus of the Next Lecture
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Next lecture will be the first among the four lectures that we plan to have on
productivity SW
That first lecture will be on word processing
We’ll learn about what we mean by word processing
We’ll discuss the usage of various functions provided by common word processors
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Lecture 14
Word Processing
Focus of the last lecture was on Application SW
Application SW are programs that interact directly with the user for the performance of
a certain type of work
That work generally falls into one of the following usage areas
Scientific/engineering/graphics
Business
Productivity
Entertainment
Educational
Today’s Lecture
First among the four lectures that we plan to have on productivity software, a subcategory
of application software
This first lecture will be on word processing
We’ll learn about what we mean by word processing and also desktop publishing
We’ll discuss the usage of various functions provided by common word processors
Word Processing
The art and science of converting written information into a form that looks pleasing
when printed
One of the most popular activities on the PC
14.1 Word Processor
The tool used to perform word processing
Long time ago, a word processor was a HW/SW combination used solely for performing
the word processing task. It looked like a computer terminal or a PC, but could do only
one task – word processing
Today, the term “word processor” generally means the SW used on a computer to
perform the task of word processing
Uses of Word Processors
Write a letter
Address labels
Research paper or report
Advertisement
Newsletter
Magazines
Book
And thousands of other tasks
Common Features
Type, cut, copy, paste, move text
Automatic line-breaks
Change font type, face, size, color
Change number of columns
Adjust margins and line, word, letter spacing
Have running headers, footers, page nos.
Insert tables, charts, graphics, drawings
Evolution of WP’s
Manual & electric typewriters (1930-1960)
Were page oriented
Type face/size was changed by replacing the typing ball
Typewriters with magnetic storage (1960’s)
IBM added storage capability using magnetic tape
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Line editors on computers(1960's)
Stand alone word processors (1960's-1970's)
cost: $15,000 to 20,000
Current WP programs on uCs (1980's onwards)
14.2 Types: WYSIWYG-based & Markup-based
All early WP’s and some of the modern ones as well are markup-based: similar to
HTML
Generally are harder to learn, but may provide better control and smaller file size
Example: LaTeX
Most current PC-based WP’s belong to the WYSIWYG category
Easy to get started due to the WIMP interface
Example: MS Word, Corel WordPerfect, Sun Star
14.3 Desktop Publishing (DTP)
A combination of word processing and graphic design. Used to develop elegant
documents
In the olden times, DTP was used for designing magazines, newspapers & other
professional-looking items
These days, because of the low cost of DTP SW, it is being used for less-demanding and
ordinary tasks as well
The original Macintosh PC started the era of DTP or “Personal Publishing” in 1984
DTP –vs– WP
The difference between the two is diminishing with time
Most WP’s now include many tools that, not long ago, were found only in DTP SW
Generally, DTP SW is a bit more difficult to use for us common computer users,
whereas WP SW is quite user-friendly
DTP SW generally provides finer control over the design/layout of a document
DTP: Requirements
High-end PC with a large-screen monitor
Laser printer
Scanner
DTP SW
Examples:
Adobe PageMaker
QuarkXPress
Corel Ventura
MS Publisher
14.4 Word Processors for the Web
Most common WP’s and DTP packages now have the Web development ability
They also include features like auto-recognition of eMail addresses and URL’s
However, specialized SW just for developing Web pages and sites is also available
Examples: DreamWeaver, FrontPage
The right font face & size for normal text
If text is too small, it becomes hard to read
Too large, wastage of space is the result. Plus the reader has to turn more pages than
necessary
Either way, the reader gets annoyed
For general WP, 10-12 point size works well
Most users, either use the Times New Roman or Arial/Helvetica type face
Bold, Italic, Underlined Text
Bold – fat
Italic – slanted (Why the name italic?)
Underlined
All used to emphasize a certain segment of text
Plea:
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Please do not over-do them
Their over-use makes it very difficult for the reader
And please, use one at a time: Text that is no only bold but also italic & underlined looks
+ively awful
Select, Cut, Copy, Drag, Paste
Just select and cut or copy or drag
Can also paste after a cut or a copy
Just think about the pain that people suffered before the advent of the modern WP’s
Movement of a single sentence from one page to another would have required re-doing
all the pages in between
Spelling & Grammar
Grammar checkers are not very helpful yet, but still useful and are improving with time
Warning: Spell checkers are not all that smart! Use them with care.
Disadvantage: My spelling ability is deteriorating day-by-day because of over-reliance on
WP spell-checkers. I am having great difficulty in writing even short-ish hand-written
notes without spelling errors
Thesaurus
My favorite tool
Helps you find synonyms and, sometimes, antonyms as well
Tables
Tables are sometimes useful for presenting info in an ordered fashion
Most WP’s provide extensive table construction & manipulation features
Graphics & Drawings
You can insert graphics that are made using other apps into a WP document
Several WP’s have a built-in drawing tool, which can be used for adding simple diagrams
(e.g. a flow chart, a simple street map) into a WP document
The Best Feature: Undo
Allows you to recover from your mistakes
Allows you to experiment without risk
Document View Mode
Most WP’s provide several ways of viewing a document
I normally work in and recommend what is known as the “Print Layout” view mode
In this view, the WP works in a true WYSIWYG mode
Print-Preview & Printing
Make sure to preview your document before printing it
Do this to make sure about the”look” of the document before it is printed
Most people these days either use inkjet printers or laser printers
Color inkjet printers cost less but are slower
B&W laser printers cost around twice as much, but are faster and generally have finer
resolution
Color laser printers are expensive
Automation
Table of contents
TOC can be automatically generated
Page nos. in the TOC get readjusted automatically
Index
Can be automatically generated
Page nos. in the index get readjusted automatically
Application of predefined styles
Change style; text changes automatically throughout the doc
Headers & Footers
Page numbers
Spelling error auto-highlight
Getting On-Screen Help
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All WP’s generally have some form of built-in help mechanism
To me, it seems like that many of those help-systems are designed to be “not-veryhelpful”:
they make finding answers to simple questions quite difficult
Nevertheless, do try them when you are searching for answers
14.5 Let’s try to use MS Word for creating a CV
(Remember the TOC)
Today’s Lecture was the …
First among the four lectures that we plan to have on productivity software, a subcategory
of application software
This first lecture was on word processing
We learnt about what we mean by word processing and also desktop publishing
We also discussed the usage of various functions provided by common word processors
Focus of the Next Lecture: Algorithms
To become familiar with the concept of algorithms
What they are?
What is there use?
To become able to write algorithms for simple problems
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Lecture 15
More on Interactive Forms
(Web Development Lecture 5)
Focus of the last lecture was on Interactive Forms
We looked at the utility of forms on Web pages
We found out about the various components that are used in a form
We became able to build a simple, interactive form
In Today’s Lecture …
We will learn ways of adding more interactivity to forms
We will get our first taste of JavaScript – the object-based language that we will be
employing throughout the rest of the Web development part of this course
Last time we mentioned server-side scripts; today we will write (simple) client-side scripts
in JavaScript
15.1 Single-Line Text Input Field
<INPUT
type=“text”
name=“name”
size=“widthInCharacters”
maxlength=“limitInCharacters”
value=“initialDefaultValue”
>
15.2 Password Input Field
<INPUT
type=“password”
name=“name”
size=“widthInCharacters”
maxlength=“limitInCharacters”
value=“initialDefaultValue”
>
15.3 Hidden Input
<INPUT
type=“hidden” name=“name”
value=“value”
>
15.4 Checkbox Input Element
<INPUT
type=“checkbox”
name=“name”
checked
value=“checkedValue”
>
15.5 Radio Button Input Element
<INPUT
type=“radio”
name=“name”
checked
value=“selectedValue”
>
15.6 File Upload Input Element
<INPUT
type=“file”
name=“name”
value=“nameOfSelectedFile”
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enctype=“fileEncodingType”
>
15.7 Reset Button Input Element
<INPUT
type=“reset”
value=“buttonLabel”
>
15.8 Submit Button Input
<INPUT
type=“submit” name=“name”
value=“buttonLabel”
>
8 Possible Values for the “type” Attribute of <INPUT> tag
text
password
hidden
checkbox
radio
file
reset
submit
15.9 Multi-Line Text Input Area
<TEXTAREA
name=“areaName”
cols=“width”
rows=“lines”
>
initial default value
</TEXTAREA>
15.10 Select from a (Drop Down) List
<SELECT
name=“name”
size=“numberOfDisplayedChoices”
multiple
>
<OPTION value=“value1”> text1
<OPTION value=“value2” selected> text2
<OPTION value=“value3”> text2
…
…
</SELECT>
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End of the Review of Tags Used in Forms
Now let’s take a look at a form that we constructed last time, and see how we can make
it better
Let’s now review what happens when I enter all the required info and press the “Send
eMail” button?
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This is what happens when the form is filled correctly. What if the form is filled
incorrectly?
What if the users leaves one of the essential fields, blank?
What if the user enters an illegal eMail address? Examples:
altaf2vu.edu.pk
bhola@hotmail.con
bhola@yahoo
A Reasonable Scenario
When the “Send eMail” button is clicked, the browser sends the data collected through
the form to a script running on the Web server
That server-side script:
receives that data
analyzes it
discovers the missing or incorrect data
sends a message back to the user’s browser stating the problem and asks the user to resend
This process …
That is the process of user:
Filling the incomplete/incorrect data
Sending it to the server
Receiving the response back from the server
Correcting and resending
is quite time-consuming and uses the server’s resources to help the user correct his
mistakes
It can really bog down the server if a large number of users are using that Web server
15.11 Client-Side Scripting is a viable alternate
In this technique, one uses the user’s browser to checking the form data
If data is missing or is incorrect, the browser can prompt the user to take corrective
action
This way, the form data is sent to the server-side script only after it has been established
that the collected data is complete and correct
15.12 Server-Side Scripts: Review
Are programs that reside on Web servers
Receive info that a user enters in a form
Process that info and take appropriate action
Examples:
CGI scripts on Unix servers
ASP scripts on Windows servers
Info contained
in the form
Acknowledgement
Message
to the
receiver’s
address
User’s
Computer
Web
Server
Server-Side
Script
Browser
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New Concept: Client-Side Scripts
Small programs that are a part of the Web page and run on the user’s (client’s) computer
They interact with the user to collect info or to accomplish other tasks
Once it has been collected, they may help pass the collected info on to a server-side
script
We’ll use JavaScript to do client-side scripting. However, there are many other languages
that can be used for that purpose, e.g. VBScript
Advantages of Client-Side Scripting
Reduced server load as it does not have to send messages to the user’s browser about
missing or incorrect data
Reduced network traffic as the form’s data is sent only once instead of many to’s and
fro’s
Disadvantages
Client-side scripts do not work with all browsers
Some user intentionally turn scripting off on their browsers
This increases the complexity of the Web page, as it now has to support both situations:
browsers with scripting capability, and those not having that capability
<INPUT
type=“submit”
name=“sendEmail”
value=“Send eMail”
>
Code for the simple “Send eMail”
button as was described during
the last Web development lecture
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This is one way of including JavaScript code in an HTML document – that is, including a
short JavaScript segment as part of an HTML tag
There are a few others as well. Let’s now find out about another.
But before we do that …
… let’s just make clear why we are interested in including JavaScript in our Web pages
15.13 Why JavaScript?
HTML is great for static Web pages; however, supports only rudimentary interactivity
through forms and hyperlinks
JavaScript can be used (along with HTML) to develop interactive content for the Web
What is JavaScript?
A programming language specifically designed to work with Web browsers
It is designed to be used for developing small programs – called scripts – that can be
embedded in HTML Web pages
JavaScript:
Is an interpreted language
Supports event-driven programming
Is object-based
Object Based?
Everything that JavaScript manipulates, it treats as an object – e.g. a window or a button
An object has properties – e.g. a window has size, position, status, etc.
Properties are modified with methods – e.g. a resize a window with resizeTo(150, 200)
<INPUT
type=“submit”
name=“sendEmail”
value=“Send eMail”
onMouseOver=
“if (document.sendEmail.sender.value.length< 1)
window.alert(‘Empty From field! Please
correct’)”
>
Additional JavaScript code for the smart
“Send eMail” button that would not allow itself
to be clicked if the “From” text field is left
<INPUT
type=“submit”
name=“sendEmail”
value=“Send eMail”
onMouseOver=
“if (document.sendEmail.sender.value.length < 1)
window.alert(‘Empty From field! Please correct’)”
>
Event
Handler
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<INPUT
type=“submit”
name=“sendEmail”
value=“Send eMail”
onMouseOver=
“if (document.sendEmail.sender.value.length < 1)
window.alert(‘Empty From field! Please correct’)”
>
<INPUT
type=“submit”
name=“sendEmail”
value=“Send eMail”
onMouseOver=“checkForm()”
>
<INPUT
type=“submit”
name=“sendEmail”
value=“Send eMail”
onMouseOver=
“if (document.sendEmail.sender.value.length < 1)
window.alert(‘Empty From field! Please correct’)”
>
checkForm()
JavaScript understands onMouseOver – it is one of the pre-defined keywords in
JavaScript
However, the case for checkForm() is different
A checkForm() function does not exist in JavaScript. Therefore, we will have to define it
ourselves
It can either be defined in the HEAD portion or BODY portion. We will do it in the
HEAD.
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We have looked at 2 techniques for embedding JavaScript code in a Web page:
1. Put the code in the tag for the “Send eMail” button - as was shown to you earlier
2. Put the checkForm() code in the HEAD portion & put the
onMouseOver=“checkForm()” attribute in the tag for the “Send eMail” button
Both perform the required function satisfactorily.
Q: Which of two techniques is better?
The “put all code in the tag” technique seems to require less code
For very short scripts, “all code in the tag” works well. However, this technique does
not work when one needs to put multiple script statements in the same tag
The “code in the HEAD portion” is more general-purpose, and the right choice for
developing larger JavaScript scripts
The main code segment that goes between the <SCRIPT>, </SCRIPT> tags in the
HEAD:
function checkForm() {
if ( document.sendEmail.sender.value.length < 1) {
window.alert( “Empty From field! Please correct” );
}
}
The JavaScript code included as an attribute of the “Send eMail” button:
onMouseOver=“checkForm()”
Today we checked if the “From” field of the form was empty
How can we modify the JavaScript code for checking if the “To” field is empty as well?
How about checking all four fields?
How about checking if the addresses given in the “From” and “To” fields are legal eMail
addresses?
Please try thinking about those possibilities?
In Today’s Lecture …
We learnt ways of constructing forms that were a bit more interactive
We got our first taste of JavaScript – the object-based language that we will be
employing throughout the rest of the Web development part of this course
Last time we mentioned server-side scripts; today we wrote (simple) client-side scripts in
JavaScript
Next (the 6th) Web Dev Lecture:
JavaScript Object, Properties, Methods
We will have a more formal introduction to JavaScript and client-side scripting
We will become able to appreciate the concept of objects in JavaScript
We will learn about the properties of those objects
We will become able to perform simple tasks through the application of methods
<HTML>
<HEAD>
<TITLE>Send an eMail</TITLE>
<SCRIPT>
function checkForm() {
if ( document.sendEmail.sender.value.length < 1) {
window.alert( “Empty From field! Please correct” );
}
}
</SCRIPT>
</HEAD>
<BODY bgcolor=“#FFFFCC”>
… body content …
</BODY>
</HTML>
JavaScript code
enclosed in the new
<SCRIPT>,</SCRIPT
> HTML tags
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Lecture 16
Algorithms
Focus of the last lecture was on Word Processing
First among the four lectures that we plan to have on productivity software, a subcategory
of application software
That first lecture was on WP
We learnt about what we mean by WP and also desktop publishing
We also discussed the usage of various functions provided by common WP’s
The Objective of Today’s Lecture
To become familiar with the concept of algorithms:
What they are?
What is their use?
What do they consist of?
What are the techniques used for representing them?
Solving Problems (1)
When faced with a problem:
We first clearly define the problem
Think of possible solutions
Select the one that we think is the best under the prevailing circumstances
And then apply that solution
If the solution woks as desired, fine; else we go back to step 2
Solving Problems (2)
It is quite common to first solve a problem for a particular case
Then for another
And, possibly another
And watch for patterns and trends that emerge
And to use the knowledge form those patterns and trends in coming up with a general
solution
Solving Problems (3)
It helps if we have experienced that problem or similar ones before
Generally, there are many ways of solving a given problem; the best problem-solvers
come-up with the most appropriate solution more often than not!
The process that can be used to solve a problem is termed as the “algorithm”
Algorithm:
Sequence of steps that can be taken to solve a given problem
Examples
Addition
Conversion from decimal to binary
The process of boiling an egg
The process of mailing a letter
Sorting
Searching
sequenscteeps
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Let us write down the algorithm for a problem that is familiar to us
Converting a decimal number into binary
16.1 Algorithm for Decimal-to-Binary Conversion
Write the decimal number
Divide by 2; write quotient and remainder
Repeat step 2 on the quotient; keep on repeating until the quotient becomes zero
Write all remainder digits in the reverse order (last remainder first) to form the final
result
Points to Note:
The process consists of repeated application of simple steps
All steps are unambiguous (clearly defined)
We are capable of doing all those steps
Only a limited no. of steps needs to be taken
Once all those steps are taken according to the prescribed sequence, the required result
will be found
Moreover, the process will stop at that point
16.2 Algorithm (Better Definition)
1st Definition:
Sequence of steps that can be taken to solve a problem
Better Definition:
A precise sequence of a limited number of unambiguous, executable steps that terminates in the
form of a solution
Three Requirements:
Sequence is:
Precise
Consists of a limited number of steps
Each step is:
Unambiguous
Executable
The sequence of steps terminates in the form of a solution
Convert 75 to Binary
2 75
37
1
2
18
1
2
9
0
2
4 1
2
2 0
2
1
0
2
0
1
1001011
remainder
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16.3 Why Algorithms are Useful?
Once we find an algorithm for solving a problem, we do not need to re-discover it the
next time we are faced with that problem
Once an algorithm is known, the task of solving the problem reduces to following
(almost blindly and without thinking) the instructions precisely
All the knowledge required for solving the problem is present in the algorithm
Why Write an Algorithm Down?
Written form is easier to modify and improve
Makes it easy when explaining the process to others
16.4 Analysis of Algorithms
Analysis in the context of algorithms is concerned with predicting the resources that re
requires:
Computational time
Memory
Bandwidth
Logic functions
However, Time – generally measured in terms of the number of steps required to
execute an algorithm - is the resource of most interest
By analyzing several candidate algorithms, the most efficient one(s) can be identified
Selecting Among Algorithms
When choosing among competing, successful solutions to a problem, choose the one which is the least
complex
This principle is called the “Ockham’s Razor,” after William of Ockham - famous 13-th
century English philosopher
Early History:
Search for a Generic Algorithm
The study of algorithms began with mathematicians and was a significant area of work
in the early years
The goal of those early studies was to find a single, general algorithm that could solve all
problems of a single type
Origin of the Term “Algorithm”
The name derives from the title of a Latin book: Algoritmi de numero Indorum
That book was a translation of an Arabic book: Al-Khwarizmi Concerning the Hindu
Art of Reckoning
That book was written by the famous 9-th century Muslim mathematician, Muhammad
ibn Musa al-Khwarizmi
16.5 Al-Khwarzmi
Al-Khwarizmi lived in Baghdad, where he worked at the Dar al-Hikma
Dar al-Hikma acquired and translated books on science and philosophy, particularly
those in Greek, as well as publishing original research
The word Algebra has its origins in the title of another Latin book which was a
translation of yet another book written by Al-Khwarzmi:
Kitab al-Mukhtasar fi Hisab al-Jabr wa'l-Muqabala
Al-Khwarizmi’s Golden Principle
All complex problems can be and must be solved
using the following simple steps:
Break down the problem into small, simple sub-problems
Arrange the sub-problems in such an order that each of them can be solved without
effecting any other
Solve them separately, in the correct order
For your own use in the future, so that you don’t have to spend the time for rethinking it
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Combine the solutions of the sub-problems to form the solution of the original problem
That was some info on history.
Now, let us to take a look at several types of algorithms & algorithmic strategies
16.6 Greedy Algorithm
An algorithm that always takes the best immediate, or local solution while finding an
answer
Greedy algorithms may find the overall or globally optimal solution for some
optimization problems, but may find less-than-optimal solutions for some instances of
other problems
KEY ADVANTAGE: Greedy algorithms are usually faster, since they don't consider the
details of possible alternatives
Greedy Algorithm: Counter Example
During one of the international cricket tournaments, one of the teams intentionally lost a
match, so that they could qualify for the next round
If they had won that particular match, some other team would have qualified
This is an example of a non-greedy algorithm
Greedy Algorithm: Example
A skier skiing downhill on a mountain wants to get to the bottom as quickly as possible
What sort of an algorithm should the skier be using?
The greedy-algorithm approach will be to always have the skies pointed towards the
largest downhill slope (dy/dx), at all times
What is the problem with that approach?
In what situations that will be the best algorithm?
In which situations would it perform poorly?
16.7 Deterministic Algorithm (1)
An algorithm whose behavior can be completely predicted from the inputs
That is, each time a certain set of input is presented, the algorithm gives the same results
as any other time the set of input is presented.
16.8 Randomized Algorithm (1)
Any algorithm whose behavior is not only determined by the input, but also values
produced by a random number generator
These algorithms are often simpler and more efficient than deterministic algorithms for
the same problem
Simpler algorithms have the advantages of being easier to analyze and implement.
16.9 Randomized Algorithm (2)
These algorithm work for all practical purposes but have a theoretical chance of being
wrong:
Either in the form of incorrect results
Or in the form of impractically long running time
Example: Monte Carlo algorithms.
16.10 Deterministic Algorithm (2)
There can be degrees of deterministic behavior: an algorithm that also uses a random
number generator might not be considered deterministic
However, if the "random numbers" come from a pseudo-random number generator, the
behavior may be deterministic
Most computing environments offer a “pseudo random number generators,” therefore,
most randomized algorithms, in practice, behave deterministically!
16.11 Heuristic
A procedure that usually, but not always, works or that gives nearly the right answer
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Some problems, such as the traveling salesman problem, take far too long to compute an
exact, optimal solution. A few good heuristics have been devised that are fast and find a
near-optimal solution more often than not
Is a heuristic, an algorithm? Yes? No? Why?
A Few Questions
Is that the best possible sequence?
How do you know?
How do I determine the best sequence?
16.12 The Brute Force Strategy (1)
A strategy in which all possible combinations are examined and the best among them is
selected
What is the problem with this approach?
A: Doesn’t scale well with the size of the problem
How many possible city sequences for n=6? For n=60? For n=600?
16.13 The Brute Force Strategy (2)
However, with the relentless increase in computing power, certain problems that – only
a few years ago - were impossible to solve with brute force, are now solvable with this
technique
16.14 A Selection of Algorithmic Application Areas
Search
Sort
Cryptography
Parallel
Numeric
Graphical
Quantum computing
Combinatory
We’ll now talk about the various ways of representing algorithms.
But, before we do that please allow me to say a few words about …
The Traveling Salesman Problem
A salesman needs
to visit each of the n
cities one after the
other and wants to
finish the trip where
it was started
Determine the
sequence of cities
such that the
traveling distance is
minimized
2
6
5
4
3
1
A possible sequence for n =
6
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Now onto Algorithm Representation
We have said enough about algorithms – their definition, their types, etc.
But, how do we actually represent them?
Generally, SW developers represent them in one of three forms:
Pseudo code
Flowcharts
Actual code
Pseudo Code
Language that is typically used for writing algorithms
Similar to a programming language, but not as rigid
The method of expression most suitable for a given situation is used:
At times, plain English
At others, a programming language like syntax
16.15 Flowchart
A graphical representation of a process (e.g. an algorithm), in which graphic objects are
used to indicate the steps & decisions that are taken as the process moves along from
start to finish
Individual steps are represented by boxes and other shapes on the flowchart, with arrows
between those shapes indicating the order in which the steps are taken
An algo. is “correct” if its:
– Semantics are
correct
– Syntax is correct
Semantics:
The concept embedded in
an algorithm (the soul!)
Syntax:
The actual representation
of an algorithm (the body!)
WARNINGS:
1. An algo. can be
syntactically correct, yet
semantically incorrect –
very dangerous
situation!
2. Syntactic correctness
is easier to check as
compared with semantic
Syntax & Semantics
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In Today’s Lecture, We …
Became familiar with the concept of algorithms:
What they are?
What is their use?
What do they consist of?
What are the techniques used for representing them?
Next Lecture: Algorithms II
We will continue our discussion on algorithms during the next lecture
In particular, we will discuss the pseudo code and flowcharts for particular problems
We will also discuss the pros and cons of these two algorithm representation techniques
i.e. pseudo code and flow charts
Start or stop
Process
Input or output
Connector
Decision
Flow line
Off-page connector
Flowchart
Elements
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Lecture 17
Algorithms II
Focus of the last lecture was on Algorithms
Became familiar with the concept of algorithms:
What they are? (SEQUENCE OF STEPS)
What is their use?
What are their types?
What are the techniques used for representing them?
Pseudo code
Flowcharts
Actual code
Today …
We will continue our discussion on algorithms that we started during the 16th lecture
In particular, we will look at the building blocks that are used in all algorithms
We will also discuss the pseudo code and flowcharts for particular problems
In addition, we will outline the pros and cons of those two techniques
17.1 Algorithm Building Blocks
All problems can be solved by employing any one of the following building blocks or
their combinations
Sequences
Conditionals
Loops
OK. Now on with the three building blocks of algorithms. First ..
Start or stop
Process
Input or output
Connector
Decision
Flow line
Off-page connector
Flowchart
Elements
This review was essential because we will be using these building blocks quite often today.
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We will now present the algorithm for a problem whose solution is familiar to us
We will first go through the problem statement and then present the algorithm in three
different formats:
Sequences
A sequence of instructions that are
executed in the precise order they
are written in:
statement block 1
statement block 2
statement block 3
statement block 1
statement block 2
statement block 3
Conditionals
Select between alternate courses of action
depending upon the evaluation of a condition
If ( condition = true )
statement block 1
Else
statement block 2
End if
statement
block 1
condition
True False
statement
block 2
Loops
Loop through a set of statements as long as
a condition is true
Loop while ( condition = true )
statement block
End Loop
True condition
False
statement
block
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1. Pseudo code
2. Flowchart
3. Actual code
Problem Statement
Convert a decimal number into binary
We did write down the pseudo code for this problem last time. Lets do it again, and in a
slightly more formal way
17.2 Solution in Pseudo Code
Let the decimal number be an integer x, x > 0
Let the binary equivalent be an empty string y
Repeat while x > 0 {
Determine the quotient & remainder of x ÷ 2
y = CONCATENATE( remainder, y )
x = quotient
}
Print y
Stop
Q: Is this the only possible algorithm for converting a decimal number into a binary
representation?
If not, then is this the best?
In terms of speed?
In terms of memory requirement?
In terms of ease of implementation?
You must ask these questions after writing any algorithm
17.3 Tips on Writing Good Pseudo Code
Convert 75 to Binary
2 75
37
1
2
18
1
2
9
0
2
4 1
2
2 0
2
1
0
2
0
1
1001011
remainder
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Use indention for improved clarity
Do not put “code” in pseudo code – make your pseudo code language independent
Don’t write pseudo code for yourself – write it in an unambiguous fashion so that
anyone with a reasonable knowledge can understand and implement it
Be consistent
Prefer formulas over English language descriptions
Does the flowchart depict the “correct” algorithm?
What do we mean by “correct”, or better yet, what do we check for “correctness”?
One way is to check the algorithm for a variety of inputs
Does it perform satisfactorily for:
x = 0 ?
negative numbers?
numbers with fractional parts?
Start
Find quotient
& remainder
of x ÷ 2
Get x
x>0 ?
Print y
S
y = CONC(remainder, x)
x = quotient
x is the decimal number
y is the binary equivalent
Flowchart of
Decimal
to Binary
Conversion
Yes No
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Strategy
<SCRIPT>
x = 75; // x is the decimal number
y = “”; // y is the binary equivalent
while ( x > 0) {
remainder = x % 2;
quotient = Math.floor( x / 2 );
y = remainder + y;
x = quotient;
}
document.write(“y = ” + y);
</SCRIPT>
Decimal to Binary Conversion in JavaScript
NOTE: Don’t worry if
you don’t understand
this code for now; you
will - later!
Another Example: Sorting
Sort the following objects w.r.t. their
heights
Expected Result
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There are many strategies for solving this problem. We demonstrate a simple one:
Repeat the following steps while the list is un-sorted:
Start with the first object in the list
Swap it with the one next to it if they are in the wrong order
Repeat the same with the next to the first object
Keep on repeating until you reach the last object in the list
Q: Is the list sorted?
A: No
Back to the Objects to be Sorted
Sorting: Step A1
Sorting: Step A1
Swap? Yes
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Sorting: Step A2
Sorting: Step A2
Swap? Yes
Sorting: Step A3
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Q: Is the list sorted?
A: No
Sorting: Step A3
Swap? No
Sorting: After Step A7
Sorting: Step B1
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Sorting: Step B1
Swap? Yes
Sorting: Step B2
Sorting: Step B2
Swap? No
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Q: Is the list sorted?
A: No
Sorting: After Step B7
Sorting: Step C1
Sorting: After Step C7
Sorting: Step C1
Swap? No
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Q: Is the list sorted?
A: Yes
STOP
Let’s now look at this same process of sorting being applied to a bigger list
---FLASH MOVIE FOR BUBBLE SORT GOES HERE---
Dim swapFlag As Boolean, list(8) As Integer
readList( list() ) ‘this needs to be defined
swapFlag = True
Do While swapFlag = True
For n = 1 To 8
If list(n) > list(n + 1) Then
temp = list(n)
list(n) = list(n + 1)
list(n + 1) = temp
swapFlag = True
End If
Next
Loop
For n = 1 To 8
Debug.Print list(n)
Next
Q: Is this the only possible algorithm for sorting a list?
A: Certainly not! In fact this one (called the “Bubble sort”) is probably the worst
(reasonable) algorithm for sorting a list – it is just too slow
You will learn a lot more about sorting in your future courses
Start
n = n+1
Get list
list
sorted?
Stop SWAP
list[n], list[n+1]
list is an array containing the heights
N is the total number of objects in the list
Flowchart for the Sorting Process
No
Yes
n = 0
list[n] >
list[n+1]?
Yes No
n>N ?
Yes
No
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17.4 Pros and Cons of Flowcharts (1)
I personally don’t find flowcharts very useful
The process of writing an algorithm in the form of a flowchart is just too cumbersome
And then converting this graphical form into code is not straight forward
However, there is another kind of flowcharts – called Structured Flowcharts – that may
be better suited for software developers
17.5 Pros and Cons of Flowcharts (2)
The good thing about flowcharts is that their symbols are quite intuitive and almost
universally understood
Their graphical nature makes the process of explaining an algorithm to one’s peers quite
straightforward
17.6 Pros and Cons of Pseudo Code (1)
Quite suitable for SW development as it is closer in form to real code
One can write the pseudo code, then use it as a starting point or outline for writing real
code
Many developers write the pseudo code first and then incrementally comment each line
out while converting that line into real code.
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