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CS101 short notes

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cs101 short notes Part 1

Charles Babbage (1791-1871)

·         Creator of the Analytical Engine - the first general-purpose digital computer (1833)
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

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.
1.    Fast
2.    Bored
3.    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  …

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.



Vacuum Tube – 1904

A vacuum tube is just that: a glass tube surrounding a vacuum (an area from which all gases has been removed). A British scientist named John A. Fleming made a vacuum tube known today as a diode. Then the diode was known as a "valve,"

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 StateUniversity during 1937-42.

Harvard Mark 1 – 1943
Howard Aiken and Grace Hopper designed the MARK series of computers at Harvard University. 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.
ENIAC – 1946
ENIAC (Electrical Numerical Integrator AndCalculator). The U.S. military sponsored their researchIt 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.
Transistor
The first transistor was invented at Bell Laboratories on December 16, 1947 by William Shockley. Compared to vacuum tubes, it offered:
  • smaller size
  • better reliability
  • lower power consumption
  • lower cost
Floppy Disk – 1950:
Invented at the Imperial University inTokyo by Yoshiro Nakamats. 
UNIVAC 1 – 1951
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. 

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)

ARPANET – 1969
            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

Intel 4004 – 1971

The 4004 was the world's first universal microprocessor.
Altair 8800 – 1975
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.
Cray 1 – 1976  
The Cray 1 was the world's first "supercomputer," a machine that leapfrogged existing technology when it was introduced in 1971.
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 price tag started at $1,565, which would be nearly $4,000 today.
Apple Macintosh – 1984
Apple introduced the Macintosh to the nation onJanuary 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.

World Wide Web -1989
WWW quickly gained great popularity among Internet users.
What is World Wide Web?
·         A huge resource of information
·         Logically unified:  Any one from any where can access the information using a very simple scheme consisting of links & URLs
·         Physically distributed:  The information is stored on Internet-connected computers that are spread all over the globe
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.

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.
How many Web pages are there?
  • In 1999 there were 800 million Web pages (15 terra (1012) bytes of text)
  • In year 2002, the number is supposed to be 8 billion
  • If you spend a minute reviewing each of these pages, it will take more than 15,000 years to go through them all
What is secret behind the explosive growth of the Web?
  • Anarchy – any page is allowed to link to any other
  • There are no controls over who puts what on the Web
    Everyone can put whatever they want to put on the Web – and they do!
The most popular Web sites?

       AOL – Most popular ISP’s Web site
  • Microsoft – Most popular software developer’s Web site
  • Yahoo – Most popular multi-service Web site
  • Amazon – most popular shop on the Web
  • CNN – most popular news Web site
  • Google – most useful search engine

CS101 short notes Part 2

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.
What is a Web Search Engine?
·         Search engines continuously scan the Web and compile a list of all the Web pages that they find
Internet & Web 
  • The “Internet” and the “Web” are not the same
  • In fact, the “Web” is a service that runs over the “Internet”. In addition to the Web, there are many other services that run over the Interne.
  • Internet is like the network of roads in a city, whereas Web is a service like the Bus Service that run over those roads. Just like other services can use the roads (e.g. wagons),
Info is available on Web
Information about almost every thing known to mankind and then some!
The info is in the form of:
 – Text
 – Graphics
 – Animation
 – Video
 – Sound
The Semantic Web
  • What unique feature distinguishes the Web of today with the Semantic Web of tomorrow?
  • Whereas, today’s Web’s content is designed for humans to read; the Semantic Web’s content will be designed for computers to understand meaningfully
  • However, the Semantic Web is not a replacement but an extension of the present Web, in which information is given well defined meaning
  • Some progress is already being made for adding “Semantic Content” on to the Web, but a lot more will happen in the next 5 years
Computer Types 
Computer types according to capability are
  • Supercomputers
  • Mainframes
  • Servers
  • Desktops
  • Portables
Supercomputers 
  • State-of-the-art machines designed to perform calculations as fast as the current technology allows
  • Used to solve extremely complex and large-scale problems: weather prediction, simulation of atomic explosions; aircraft design; movie animation
  • Cost tens of millions of dollars
The Champion: ASCI White
  •  Most powerful computer as of February 2002
  • Capable of 12.3 trillion calculations/sec
          - 74,000 times faster than Cray 1 (1976)
          - 1,000 times faster than Deep Blue (1997)
  • Designed for complex 3-D simulations required for testing nuclear weapons
  • Powered by 8192 microprocessors
  • 6 TB of memory; 160 TB of storage capacity
Mainframe Computers
  •  Also called “Enterprise Servers”
  • Designed for performing multiple, intensive tasks for multiple users simultaneously
  • Used by large businesses (e.g. banks, e-commerce sites), military, and industrial organizations
  • Designed for very-high reliability
  • Cost in millions of dollars
Servers/Minicomputers 
  • The name minicomputers used to define the class of computers that lies between personal computers and mainframes
  • Generally are more reliable than desktops, but not as solid as the mainframes
  • Costs in hundreds of thousands of dollars
Desktop Computers
  • Also called microcomputers
  • Low-end desktops are called PC’s and high-end ones “Workstations”
·         PC’s are used for running productivity applications, Web surfing, messaging
·         Workstations cost a few thousand dollars; PC around a $1000
Mobile Computers 
Laptops, palmtops, and wearable computers are very capable computers but are light-weight and consume very little power

Laptops
  • also called notebook computers
  • generally weigh around 2kg
  • use special low-power processors
  • typically have 256MB memory,
  • 40GB of storage
  • can work for more than 2 hours on battery.
  • Their usage is similar to that of PCs
    They cost in the range of $1500-2500
Palmtops,
  • also known as PDA’s - Personal Digital Assistants
    Weigh less than a pound
  • have very low-power processors
  • KB’s of memory
  • MB’s of storage capacity
  • Can run for many hours on AA batteries
  • Used as an electronic version of a pocket diary
  • Also for Web surfing and e-mail or even as mobile phones
  • Palmtops cost $200-600
Wearables
  • are small in size
  • carried in a pocket
  • worn on the arm, waist
  • or head or elsewhere on the body
  • Capability similar to PDA’s
  • but more expensive
  • They are always ON, and always accessible. That is, the user can always enter and execute commands, even while walking around or doing other activities
  • Each soldier of the future will be fitted with one
Ranking w.r.t. installed number
  •  PC’s
  • PDA’s
  • Workstations
  • Servers
  • Wearables (will take the top spot in future)
  • Mainframes
  • Supercomputers
Essential Hardware Components
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, etc.)

Software: 
The set of instructions that operates various parts of the hardware. Also termed as “computer program

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.
Memory
Memory is the electronic holding place for instructions and data that your computer's microprocessor can reach quickly.
Storage
Computer storage is the holding of data in an electromagnetic form for access by a computer processor.
Output
The devices to which the computer writes data are called Output devices
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. 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.
Joystick
In computers, a joystick is a cursor control device used in computer games.
 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. 

CS101 short notes Part 3

What is a 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.  
Many Types of Ports
  1. Parallel
  2. Serial
  3. SCSI
  4. USB
  5. Firewire
Parallel
An interface on a computer that supports transmission of multiple bits at the same time; almost exclusively used for connecting a printer.
Serial
It is a general-purpose personal computer communications port in which 1 bit of information is transferred at a time.
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.
USB
USB (Universal Serial Bus) is a plug-and-play hardware interface for peripherals such as the keyboard, mouse, joystick, scanner, printer and modem.
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.
Processor
  • Pentium
  • Celeron
  • Athlon
  • PowerPC
  • StrongARM (PDA)
  • Crusoe (Laptops)
  • SPARC (Workstations)
Memory/Storage 
RAM
RAM (random access memory) is the place in a computer where the operating system,
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. Hard disk
Hard disk is a computer storage device which saves and retrieves the data when required. Floppy disk
A diskette is a random access, removable data storage medium that can be used with personal computers.
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.
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.
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)
Output Devices 
  •  Printer
  • Plotter
  • Speakers
  • Monitor
Modem is output as well as input device at the same time.
  • Monitor
  • Keyboard
  • Mouse
  • Speaker/headphone
  • Microphone
  • CPU
  • Front buttons
  • Backside ports, fan, slots, cables
Inside CPU
  • Power supply/fan & connectors
  • Motherboard
  • Bus
  • Edge connectors
  • Ports
  • Video card
  • Modem
  • Network card
  • Sound card
  • ROM
  • RAM
  • Slots
  • DIMM’s
The Processor Module 
  • The slot on the motherboard
  • The housing
  • Fan
  • Heat sink
  • Pins (256?), Transistors (10 million?)
HTML Page
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>

Microprocessor
A microprocessor (abbreviated as µP or uPis 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.
Integrated circuit
  • Commonly known as an IC or a chip
  • A tiny piece of Silicon that has several electronic parts on it
Components of integrated are
  • Devices
  • Transistors
  • Diodes
  • Resistors
  • Capacitors
  • Wires
     
And are made of the following materials
 

  • Silicon - semiconductor
  • Copper - conductor
  • Silicon Dioxide - insulator
A Microprocessor System
  • Microprocessors are powerful pieces of hardware, but not much useful on their own
  • A microcomputer is 1 example of a microprocessor system
Micro Controller
  • Micro-controllers are another type of microprocessor systems
  • They are generally not that powerful, cost a few dollars a piece, and are found embedded in video games, VCRs, microwave ovens, printers, autos, etc.
The Main Memory Bottleneck
  • Modern super-fast microprocessors can process a huge amount of data in a short duration
  • They require quick access to data to maximize their performance
On-Chip Cache Memory
That small amount of memory located on the same chip as the microprocessor is called On-Chip Cache Memory
Bus Interface Unit
The bus interface unit is the part of the processor that interfaces with the rest of the PC. 
Instruction Decoder
The instruction decoder of a processor is a combinatorial circuit sometimes in the form of a read-only memory,
 decoder is a device which is the reverse, undoing the encoding so that the original information can be retrieved.
Microprocessor Building Blocks
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.


Floating-Point Unit (FPU)
floating point unit (FPU) is a part of a CPU specially designed to carry out operations on floating point numbers.

Registers
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.
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.

Control Unit
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.

Instruction Set
The set of machine instructions that a microprocessor recognizes and can execute – the only language microprocessor knows
The 1st microprocessor : Intel 4004
  • Introduced 1971
  • 2250 transistors
  • 108 kHz, 60,000 ops/sec
  • 16 pins
  • 10-micron process
  • Cost: less than $100
Currently Popular Intel Pentium 4 (2.2GHz)
  • Introduced December 2001
  • 55 million transistors
  • 32-bit word size
  • 2 ALU’s, each working at 4.4GHz
  • 128-bit FPU
  • 0.13 micron process
  • Targeted use: PC’s and low-end workstations
  • Cost: around $600
Moore’s Law
  • In 1965, one of the founders of Intel – Gordon Moore – predicted that the number of transistor on an IC (and therefore the capability of microprocessors) will double every year. Later he modified it to 18-months

Enhancing the capability of a microprocessor 

The computing capability of a microprocessor can be enhanced in many different ways:
  • By increasing the clock frequency
  • By increasing the word-width
  • Improving the architecture

CS101 short notes Part 4

Binary
(Base 2) number system
Decimal
(Base 10) number system

Binary (Base 2) number system consists of just two digits 0,1
Decimal (Base 10) number system consists of ten symbols or digits 0,1,2,3,4,5,6,7,8,9

Other popular number systems

Octalbase = 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)
Why Binary?
  • Because this system is natural for digital computers

Bit stands for Binary Digit
Byte = 8 Bits
Decimal to Binary conversion

Check 

1001011 =          1x20 + 1x21 + 0x22 + 1x23 + 0x24 + 0x25 + 1x26
             =          1 + 2 + 0 + 8 + 0 + 0 + 64
             =          75
Boolean Logic Operations 
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
· y
OR
z = x OR y
+ y
XOR
z = x XOR y
Å y
Truth Table of Logic FunctionA 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


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 Å y
0
0

0
1

1
0

1
1



Truth Table for the XOR Operation
X
y
z = x Å y
0
0
0
0
1
1
1
0
1
1
1
0

General Structure of HTML tags 
Single tag

<tagName>
Example:     <BR>

Single Tags with Attributes

<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>
Code for the List and Table
<UL>
<LI>SimCity</LI>   
<LI>Quake</LI>                   
<LI>Bridge</LI>
</UL>



<TABLE border = “1” >
<TR>
<TH>Indoor</TH>
<TH>Outdoor</TH>
</TR>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>

Lists
HTML code
Browser Display
<UL>
  <LI>SimCity</LI>
   <LI>Quake</LI>
   <LI>Bridge</LI>
</UL>
  • SimCity
  • Quake
  • Bridge

<UL>
Un-ordered List
<LI>
Line items
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
Browser Display
<UL type="circle">
  <LI>SimCity</LI>
   <LI>Quake</LI>
   <LI>Bridge</LI>
</UL>
  • SimCity
  • Quake
  • Bridge

HTML code
Browser Display
<UL type="square">
  <LI>SimCity</LI>
   <LI>Quake</LI>
   <LI>Bridge</LI>
</UL>
  • SimCity
  • Quake
  • Bridge

Q: What happens if I start a new list without closing the original one?

HTML code
Browser Display
<UL>
<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

Such structures, i.e., those in which another starts before the first list is finished, are called Nested Lists
Types of Lists
In addition to un-ordered lists, HTML supports two other types
  • Ordered Lists
  • Definition List
Ordered List

Ordered List
Browser Display
<OL>
<LI>SimCity</LI>
<LI>Quake</LI>
<LI>Bridge</LI>
</OL>
    1. SimCity
  1. Quake
  2. Bridge

Ordered List
Browser Display
<OL type = “a”>
<LI>SimCity</LI>
<LI>Quake</LI>
<LI>Bridge</LI>
</OL>
    1. SimCity
  1. Quake
  2. Bridge
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, …

Q: How would one start an ordered list with something other than 1

Ordered List
Browser Display
<OL start = 25>
<LI>SimCity</LI>
<LI>Quake</LI>
<LI>Bridge</LI>
</OL>
  1. SimCity
  2. Quake
  3. Bridge
Definition List 
Definition List
Browser Display
<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-em-up genre

<DL>
Definition List
<DT>
Term
<DD>
Definition
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

Tables

HTML code
Browser Display
<TABLE border = "1" >
<TR>
<TH>Indoor</TH>
<TH>Outdoor</TH>
</TR>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
Indoor
Outdoor
Squash
Cricket

<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
    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”>
HTML code
Browser Display
<TABLE border = "1" >
<TR>
<TH>Indoor</TH>
<TH>Outdoor</TH>
</TR>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
Indoor
Outdoor
Squash
Cricket

HTML code
Browser Display
<TABLE >
<TR>
<TH>Indoor</TH>
<TH>Outdoor</TH>
</TR>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
Indoor
Outdoor
Squash
Cricket

HTML code
Browser Display
<TABLE border=“1” >
<TR>
<TH colspan=“2”> Indoor Outdoor
</TH>
</TR>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
Indoor Outdoor
Squash
Cricket

HTML code
Browser Display
<TABLE border = "1" >
<CAPTION>
My favorite sports
</CAPTION>
<TR>
<TD>Squash</TD>
<TD>Cricket</TD>
</TR>
</TABLE>
My favorite sports
Squash
Cricket
Squash
Cricket

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
Machine Language 
  • Machine language, though readily understood by microprocessors, is very difficult to write in for human programmers
Language Translators 
  •  Human programmers write programs in a language that is easy to understand for them
Software Development
  • 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

Two Major Types of Software 

  • System SW
    Programs that 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
System Software
Operating Systems
  • It interacts directly with the computer HW
  • Other SW normally does not directly interact with the HW, but through the OS
Examples:
       Windows ,  Mac , OS , Linux , Unix , Solaris , DOS , CP/M  , VMS
Firmware
  • 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
Utilities
  • Computer programs that perform a particular function related to computer system management and maintenance
Examples:
             1- Anti-virus SW
             2- Data compression SW
             3- Disk optimization SW
             4- Disk backup SW

Language Translator

      1-  Compiler translates the program written in a HLL in one go.
      2-  nterpreter translates the HLL program one statement at time.
Device Drivers
  • A computer program that facilitates the communication between the computer and a peripheral device (e.g. printer, mouse, etc.)
Application Software
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

Another way of classifying Software

  • 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
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
Three Main Types of Software Licenses 
  1. Proprietary – Most software on a Windows PC or a Macintosh belongs to this category
  2. Freeware – Most software on a Linux PC belongs to that category
  3. Shareware – the category which lies between the above two categories
Proprietary SW License
  • The user needs to pay the maker of the SW for buying a license that allows the user to use the SW
Types of Proprietary Licenses
  • Single-user license
  • Multi-user license
  • Concurrent-user license
  • Site license
Freeware SW License
Allows the user free use of the SW
Open-Source SW License
  • Some authors give away the machine code only, which is extremely difficult to modify, if at all!
Shareware SW License
  • Allows the user free use of the SW, but with a request that the user pay the author a small amount (US$10-50) if the user is satisfied with the SW
Trialware
  • The SW is usable for a short period only

Interactive Forms (1)
  • Without forms, a Web site is “read-only” – it just provides information to the user
Interactive Forms (2)
  • Can be simple or very complex
  • Are always placed between the <BODY> and </BODY> tags of a Web page
Interactive Forms (3)
  • Text fields
  • Check boxes
  • Buttons
Server-Side Scripts
  • 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
Application Software
Application software are programs that interact directly with the user
They generally do not talk directly to the hardware


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
Classification According to Application Area
Scientific/engineering/graphics
Business
Productivity
Entertainment
Educational


Scientific SW
Simulation of natural systems
Mathematical computation packages
MathCAD
Engineering SW
Computer-aided design (CAD)
AutoCAD
Telecommunication system SW
Graphics & Animation SW (1)
Two types:
1. Vector graphics
Treats everything that is drawn as an object
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
Example:  MS Paint, Adobe Photoshop

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
E-Commerce Software
Reliability
Security
Ability to handle 1000’s of transactions, simultaneously

ERP (Enterprise Resource Planning) SW

Very large scale, complex & expensive SW
Example:  SAP, Oracle, PeopleSoft, Baan
DSS (Decision Support Systems) SW
Sometimes also called “expert systems”
Many times are based on a branch of computer science called “artificial intelligence”
Productivity SW
Most popular category in terms of licenses sold
Word Processing                       -- Spreadsheets
Presentations                 -- Databases
Word Processors
Probably the most popular productivity app
Style sheets
Spelling & grammar checking
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
Spreadsheet SW (1)
Electronic replacement for ledgers Is used for automating engineering, scientific, but in majority of cases, business calculationsm.
Spreadsheet SW (2)
Consist of cells arranged in rows and columns
Presentation Development SW
Used to prepare multimedia material for lectures & presentations to display key points, graphics, animation, or video with the help of multimedia projectors
Small-Scale Databases SW (1)
Easy to use applications designed for efficient storage and fast and easy retrieval of data

Small-Scale Databases SW (2)
Before the advent of the currently popular “relational” database model, the data basing function was performed using what is called the “flat-file” model
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
Productivity SW Suites
A set of stand-alone productivity applications designed to work easily with each other
Examples:  MS Office, Corel WordPerfect Office
Document-Centered Computing (DCC) 
The increasing cooperation among the apps included in productivity suites has given rise to a new computing model called DCC
Entertainment SW
Simple, intuitive, many times social UI’s
Music & Video Players
Music players (WinAmp)
Video/Music players (Real player, Windows Media player, QuickTime player)
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
Games
Educational (especially for toddlers)
Sports
Educational SW
Electronic Encyclopedias

Great resource of useful information presented in a very interesting format
On-Line Learning
With time, the VU Web site will become more and more focused on interactive online learning

Interactive CD’s

Same as on-line learning, but through a CD instead of a Web site
Attributes of Good Application Software
Easy to install, un-install
User Interface
Configurable
Has a tutorial and a complete help manual

CS101 short notes Part 5

Word Processing 
The art and science of converting written information into a form that looks pleasing when printed
Word Processor
  • The tool used to perform 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
Desktop Publishing (DTP)
  • A combination of word processing and graphic design. Used to develop elegant documents
 DTP: Requirements
  • High-end PC with a large-screen monitor
  • Laser printer
  • Scanner
  • DTP SW
  • Examples:
  • Adobe PageMaker
  • QuarkXPress
  • Corel Ventura
  • MS Publisher

Client Side Script 
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

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
Disadvantages
  • Client-side scripts do not work with all browsers
  • Some user intentionally turn scripting off on their browsers

JavaScript

Why JavaScript? 
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 –
Definition of Algorithm
Sequence of steps that can be taken to solve a given problem is called Algorithm.

Examples:

Addition
Conversion from decimal to binary
The process of boiling an egg
The process of mailing a letter
Sorting
Searching
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
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

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

Deterministic Algorithm
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.
Randomized Algorithm
Any algorithm whose behavior is not only determined by the input, but also values produced by a random number generator
Heuristic
A procedure that usually, but not always, works or that gives nearly the right answer
The Brute Force Strategy
A strategy in which all possible combinations are examined and the best among them is selected
A Selection of Algorithmic Application Areas
Search
Sort
Cryptography
Parallel
Numeric
Graphical
Quantum computing
Combinatory
Syntax & Semantic

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

Algorithm Building Blocks
·         Sequences
·         Conditionals
·         Loops
Strategy for Sorting
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 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

Some of things that JavaScript cannot do!
  • The following file ops. on the client computer:
       -- Read                     -- Modify
      -- Rename                 -- Delete
      -- Create
  • Create graphics (although, it does have the ability to format pages through HTML - including the placement of graphics)
Some of the things that JavaScript can do!
  • Control the appearance of the browser
  • Control the content and appearance of the document displayed in the browser
  • Store & modify a limited amount of data about the user in the form of client-side “cookies”
Client-Side JavaScript
Although a version of JavaScript exists that can be used to write server-side scripts, our focus in this course will only be on client-side scripting
Case Sensitivity
  • HTML is not case sensitive. The following mean the same to the browser:
    <HTML> -- <html>
    <Html> -- <htMl>
  • JavaScript is case sensitive. Only the first of the following will result in the desired function – the rest will generate an error or some other undesirable event:
    onMouseClick -- OnMouseClick
    onmouseclick -- ONMOUSECLICK
JavaScript is Object-Based
  • Everything that JavaScript manipulates, it treats as an object – e.g. a window or a button
Not Object-Oriented!
  • JavaScript is not a true object-oriented language like C++ or Java
  • It is so because it lacks two key features:
       -- A formal inheritance mechanism
       -- Strong typing
Types of Objects
  • JavaScript objects
       -- Objects that are part of JavaScript
       -- Examples: window, document
  • Browser objects
       -- Objects that contain info not about the contents of the display, but the browser itself
       -- Examples: history, navigator
  • User-defined object
Event Handlers
  • “Events” are actions that occur as a result of user’s interaction with the browser
  • We use “event handlers” [e.g. onMouseOver(), onClick()] to design Web pages that can react to those events
1.    Batch Programs
2.    Event-Driven Programs

Batch Programs
These are typically started from a shell (or automatically via a scheduler) and tend to follow a pattern of:
Initialize internal data
Read input data
Process that data
Print or store results

Event-Driven ProgramsExamples: GUIs, microwave, camera
The system sends events to the program and the program responds to these as they arrive.
Programming Language
A vocabulary and set of grammatical rules for instructing a computer to perform specific tasks
All programs consists of:

Sequence of instructions
Conditionals
Loops

These may contain:
Data
Input/output (print, etc)
Operations (add, divide, etc)
Examples of Prog. Languages
Types of Prog. Languages
High level Programming Languages
Low Level Programming Languages

High-level programming languages, while simple compared to human languages, are more complex than the languages the uP actually understands,
Assembly languages are similar to machine languages, but are easier to program in as they allow a programmer to substitute names for numbers



Machine languages consist of numbers

Interpreters: immediate response, but execute code slowly.
Compilers: Takes longer to compile, but super-fast execution.
Programming SW Development 
SW Design Methodology ?
The set of (often flexible) rules and guidelines a team of developers follow to construct reasonably complex SW systems
  • Object Oriented Design
  • Structured Design

CS101 short notes Part 6

Object-Oriented Languages
Programming languages specifically designed to make it easy to implement object-oriented designs   
Examples: Smalltalk, C++, Java
Variables
Variables give us the ability to manipulate data through reference instead of actual value.
Variables are names assigned to values.
Identifiers
Identifiers are names used by JavaScript to refer to variables (as well as objects, properties, methods, and functions!). An identifier must begin with an alphabetical character (a-z or A-Z) or the underscore “_” character.

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