Paper-I Introduction to Computer Science & Information Technology Chapter-2

Dept. of Computer Application, CVS, YSM

INTRODUCTION TO COMPUTER

Computer :- It is electronic device

Father:- Charles Babbage

Mother:- Lady ADA

Means:

CO -> Common

MP -> Multipurpose

U -> Unit

TER -> Terminal

PRINTERSCANNER

Features of Computer:

• Speed: Computers can carry out instructions in less than a millionth of a second.

• Accuracy : Computers can do the calculations without errors and very accurately.

• Diligence : Computers are capable of performing any task given to them repetitively.

• Storage Capacity : Computers can store large volume of data and information on magnetic media.

SOFTWARE

• Software is set of programs (which are step by step instructions) telling the computer how to process data.

• Software needs to be installed on a computer, usually from a CD.

• Softwares can be divided into two groups:

- System SW

- Application SW

System Software

• It controls the overall operation of the system.

• It is stored in the computer's memory and instructs the computer to load, store, and execute an application.

• Examples: Operating System (OS), Translators

DOS, Windows, Unix etc.

Application Software

• They are Software’s written to perform specific tasks.

• The basic types of application software are:

word processing, database, spreadsheet, desktop publishing, and communication.

Examples: MSOffice, Tally, MSOutlook,

ISBS, MODBANKER BANKSOFT

History of Evolution Of Computers

Two Eras:

• Mechanical Era (Before 1945)

• Electronic Era (1945 - )

Can be divided into generations.

• First Generation (1945 – 1954)

• Second Generation (1955 – 1964)

• Third Generation (1965 – 1974)

• Fourth Generation (1975 - )

FIRST GENERATION (1945 – 1954: The Vacuum Tube)

• The first generation of computers, characterized by vacuum tubes, started in 1951 with the creation of -

UNIVAC (Universal Automatic Computer) – a tabulating machine which won the contest for the fastest machine which could count the US 1890 census.

VACUUM TUBES – electronic tubes about the size of light bulbs.

Eg: IBM-700,IBM-701

DISADVANTAGES:

• They generate more heat causing many problems in temperature regulation and climate control.

• Tubes were subject to frequent burn-out.

SECOND GENERATION (1955 – 1964: The Transistor)

The year 1959 marked the invention of transistors, which characterized the second generation of computers.

TRANSISTOR – It was a three-legged component which shrunk the size of the first generation computers. Occupied only 1/100th of the space occupied by a vacuum tube,More reliable, had greater computational speed, required no warm-up time and consumed far less electricity.

Eg ,PDP-1,PDP-5(Programed Data Processor).

THIRD GENERATION (1965 – 1974: The Integrated Circuit)

Third generation computers arose in 1965 with the invention of smaller electronic circuits called integrated circuits (IC’S).

INTEGRATED CIRCUITS –They are square silicon chips containing circuitry that can perform the functions of hundreds of transistors.

Eg. PDP-11(16-bit), CYBER-175

ADVANTAGES:

• RELIABILITY – Unlike vacuum tubes, silicon will not break down easily. It is very seldom that you will have to replace it.

• LOW COST – Silicon chips are relatively cheap because of their small size and availability in the market. It also consumes less electricity.

FOURTH GENERATION (1975 –1984: The Microprocessor)

• Marked by the use of microprocessor

• MICROPROCESSOR – It is a silicon chip that contains the CPU – part of the computer where all processing takes place.

4004 chip – was the first microprocessor introduced by Intel Corporation.

Eg: RISC

Language: C, C++,JAVA,Oracle

FIFTH GENERATION (1985 – present: USSI (ultra large scale integration))

• It contain millions of IC’s. Use for intelligent Programming on knowledge bsed .

Types of Computers

On the basis of Computing Power & Size:

• Laptop / Palmtop

• Micro Computer / Desktop

• Mini Computer / Mainframe

• Super Computer

Language of Computers

• Computers only understand the electronic signals.

Either Current is flowing or not.

• Current Flowing : ON

• Current Not Flowing : OFF

• Binary Language

• ON : 1

• OFF : 0

Bit, Byte, KB, MB, GB ,TB

Computer Network

• A Computer Network is interconnection of Computers to share resources.

• Resources can be : Information, Load, Devices etc.

Types Of Computer Networks

On the basis of Size:

• Local Area Network (LAN)

Its a network of the computers locally i.e. in

one room, one building.

• Wide Area Network (WAN)

Its a network of the computers spread widely

geographically.

• Metropolitan Area Network (MAN)

Its a network of the computer spread over Metro cities.

Benefits of Computer Networks

• Information Sharing

• Device Sharing

• Load Sharing

• Mobility

• Fast Communication

• Anywhere Anytime Banking

Internet

• Internet is a huge network of computer networks.

Internet provides many services:

– Email - World Wide Web (www) - Remote Login (Telnet)

- File Transfer (FTP)/ - Downloading/Uploading of S/W(Software), Movie, Song etc.

- Searching Anything

There are three major component to connect a internet

Phone line

MODEM (modulator & demodulator)

Data Cable

CPU ( Central Processing Unit) :

The central processing unit (CPU), also known as just a "processor”, is the "brain" of your computer.

It contains various electronic circuits.

CPU

• The central processing unit or (CPU) is the "brain" of your computer. It contains the electronic circuits that cause the computer to follow instructions from memory.

• The CPU contains three main parts, all housed

in a single package (Chip):

– Control Unit (CU)

– Arithmetic Logic Unit (ALU)

– Memory

VDU (Monitor)

• This is the television-like screen where the results of a computer's tasks are displayed.

• Monitors come in all sizes, but most commonly they are either 15 or 17 inches

(measured diagonally from one corner of the screen to the opposite corner).

Cathode Ray Tube (CRT)

This monitor uses a Cathode Ray Tube (CRT). CRT tube creates an image on the screen using a beam of electrons. CRT consists of one or more guns that fire a beam of electrons inside the screen. The screen is coated with very tiny Phosphor dots from inside. The beam

of electrons repeatedly falls on the surface of screen. Every beam fall takes only a fraction of second. CRT in color monitors consists of three guns. These guns generate red, green and blue (RGB) colors. The other colors are generated with a combination of these three colors. Nowadays, most of the CRT monitors are replaced by Flat Panel Monitors.

Liquid Crystal DisplayLiquid crystal display screen contains a substance called liquid crystal. The molecules of this substance line up in such a way that the light behind the screens blocked or allowed to create an image. LCDs provide a sharper picture than CRTs and omit less radiation. LCD displays requires less power and take up less space than CRT.

Thin Film Transistor

A display screen made with TFT (thin-film transistor) technology is a liquid crystal display (LCD), common in notebook and laptop computers, that has a transistor for each pixel (that is, for each of the tiny elements that control the illumination of your display). Having a transistor at each pixel means that the current that triggers pixel illumination can be smaller and therefore can be switched on and off more quickly.

TFT is also known as active matrix display technology (and contrasts with "passive matrix" which does not have a transistor at each pixel). A TFT or active matrix display is more responsive to change. For example, when you move your mouse across the screen, a TFT display is fast enough to reflect the movement of the mouse cursor. (With a passive matrix display, the cursor temporarily disappears until the display can "catch up.")

LED (light-emitting diodes) monitorsLED monitors are the latest types of monitors on the market today. These are flat panel, or slightly curved displays which make use of light-emitting diodes for back-lighting, instead of cold cathode fluorescent (CCFL) back-lighting used in LCDs. LED monitors are said to use much lesser power than CRT and LCD and are considered far more environmentally friendly.

The advantages of LED monitors are that they produce images with higher contrast, have less negative environmental impact when disposed, are more durable than CRT or LCD monitors, and features a very thin design. 

Input Devices :

 > keyboard >Mouse  >Joystick > Scanner  > Light pen 

> Voice recognition device  > Graphic tablet or digitizer 

Output Devices:

> Monitor  > Printers 

> Plotters  > Speakers

Keyboard

• The keyboard looks like a typewriter.

• It contains all the letters of the alphabet, numbers and some special symbols.

• It operates like a typewriter keypad, but instead of moving an arm, which strikes the paper, it sends an electronic impulse to the computer, which displays a character on the monitor. Are of two type:

1) Standard keyboard

2) Multimedia keyboard

• Keypad contains:

– Alphabets - Numbers - Special Symbols

– Function Keys

Mouse

• Its a device that is used to control the computer. A cable connects the mouse to the computer.

• When the mouse is moved on a pad, called a mouse pad, the cursor on the screen moves.

• A cursor is a small symbol displayed on the computer screen (normally a diagonal arrow that

is used as a pointer) that shows you what the mouse is referencing on the screen.

• Pointing & Click Device.

• Two / Three Buttons

• Wheel / Optical Mouse

• Normally Left Click – Select/ Run

• Right Click – Popup Menu

Joystick

Light Pen

A light pen, also called a selector pen, is a computer input device in the form of a light-sensitive wand used in conjunction with a computer's CRT display. It allows the user to point to displayed objects or draw on the screen in a similar way to a touchscreen but with greater positional accuracy.

Scanner

• A scanner is a device used to copy an image off paper and convert it into a digital image, which can be saved as a computer file and stored on a hard drive.

• Scanners can also use a special kind of technology called Optical Character Recognition (OCR) to read text from paper and save it as an editable document file .

Magnetic Ink Card Reader(MICR)MICR input device is generally used in banks because of a large number of cheques to be processed every day. The main advantages of MICR is that it is fast and less error prone.

Optical Character Reader(OCR)OCR is an input device used to read a printed text. OCR scans text optically character by character, converts them into a machine readable code and stores the text on the system memory.

Bar Code ReadersBar Code Reader is a device used for reading bar coded data (data in form of light and dark lines). Bar coded data is generally used in labelling goods, numbering the books etc.

Optical Mark Reader(OMR)OMR is a special type of optical scanner used to recognize the type of mark made by pen or pencil. It is used where one out of a few alternatives is to be selected and marked. It is specially used for checking the answer sheets of examinations having multiple choice questions.

Plotter

The plotter was the first computer output device that could print graphics as well as accommodate full-size engineering and architectural drawings.

Printer

• A printer is designed to output information from a computer onto a piece of paper.

• There are three kinds of printers:

dot matrix, laser, and inkjet.

Dot- Matrix 

It's very old, very slow, and very noisy. IT also has a poor output quality, however it's cheap to buy and fairly reliable. 

laser Printer

The laser printer is very expensive to buy but cheap-ish to run. The output quality is very high, and it prints very fast .

Ink-Jet or Bubble-Jet 

These are cheap-ish to buy. The quality of print is high, and they are quite fast printers. However, the printer inks are very expensive, and if the print-out gets wet, it has a tendency to smear. 

A Look Inside ..

• Identify all the major components:

> Power Supply >Motherboard >Memory >Card Slots

> Cards (sound, video, network) >CPU, heatsink and fan >Drives (floppy, hard and CD-ROM)

What these components do.

• Power Supply – (Heart) supplies power to all the circuitry and devices.

• Motherboard – (Body) acts as a manager for everything on the computer – connects all the other components together.

• CPU – Central Processing Unit – (Brain) this does all the work of computing.

• RAM – Random Access Memory – (Short-term memory) holds data and program instructions that the computer is currently using.

• Hard Drive – (Long-term memory) holds all of the information that needs to be stored between uses of the computer.

• Floppy and CD-ROM drives – (Mouth/ears) allow you to give data to the computer and take data away from the computer.

• Card Slots – (Fingers) Allows other components to be added to the computer.

• Video card – (Face) Does all of the processing necessary to get stuff looking nice on screen, quickly.

• Sound card – (Vocal cords) Allows sounds from HD or CD-ROM to be played.

• Network Card – (Telephone) allows computer to talk to other computers over a wire.

Power Supply

SMPS – Switch Mode Power Supply

Switching Transistors

Outputs + 5V, -5V, +12 V, -12 V

Typical Costs are:

• ATX

• Non ATX

Usually, SMPS comes with the CPU Cabinet.

Storage Devices

I. Secondary Memory

II. Primary Memory

a) RAM

i. SRAM ii. DRAM

b) ROM

i. PROM ii. EPROM

c) Hybrid

i. EEPROM ii. NVRAM iii. Flash Memory

d) Cache Memory e) Virtual Memory

RAM

ROM

Read-only memory (ROM) is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware (software that is very closely tied to specific hardware, and unlikely to need frequent updates).

Cache Memory

“A computer memory with very short access time used for storage of frequently used instructions or data” .

Virtual Memory

It is a computer system technique which gives an application program the impression that it has contiguous working memory (an address space), while in fact it may be physically fragmented and may even overflow on to disk storage.

Hard Drive

• Magnetic Memory Device.

• Non-removable storage device.

• Several Circular Magnetic Disks are housed in a single case.

• Data is stored as 1s & 0s.

• Typical Capacity is 20 GB -80 GB

Serial Advance Technology Attachment (SATA) is connecting devices like optical drives and hard drives to the motherboard.SATA cables are long, thin, 7-pin cables. One end plugs into a port on the motherboard.he other into the back of a storage de like a hard drive.

Parallel Advance Technology Attachment (PATA) is an IDE standard for connecting storage devices like hard drives and optical drives to the motherboard.

PATA cables are long, flat cables with 40-pin connectors (in a 20x2 matrix) on either side of the cable. One end plugs into a port on the motherboard, usually labeled IDE, and the other into the back of a storage device like a hard drive.

Floppy Drive

• Magnetic Memory Device.

• Removable storage.

• A single circular mylar plastic disk, coated with magnetic material is packed in a protective plastic casing.

• Typical size is 3.5” & Capacity is 1.44MB

CD-ROM Drive (Compact Disc Read Only)

• Optical Device.

• Removable Storage.

• Read Only Memory.

• Typical Capacity is 550 Mb – 800MB

• Typical Costs are:

• Related Terms:

• CD Writer

• WORM

• CD RW

DVD Drive (Digital Versatile Disk)

Difference between CD & DVD

1. DVDs have over 6 times more capacity than CDs at the minimum2. DVDs are preferred for movies and Software.

3.  CDs are still the preferred in publishing music albums because of cost.4. DVD players can play both CDs and DVDs while CD players can only play CDs.

Ribbon Cables

Video Card

Sound Card

Computer Peripherals

Major Peripherals

• Keyboard

• Mouse

• Hard Disk

• Floppy Disk

• CD ROM

• Printer

• Scanner

• Joystick

Some Important Term Related To Computer

Bug: A software bug is an error, flaw, mistake, failure, or fault in a computer program or system that produces an incorrect or unexpected result, or causes it to behave in unintended ways. Most bugs arise from mistakes and errors made by people in either a program's source code or its design, and a few are caused by compilers producing incorrect code.

Debug: Debugging is a methodical process of finding and reducing the number of bugs, or defects, in a computer program or a piece of electronic hardware, thus making it behave as expected.

Compiler: A compiler is a computer program (or set of programs) that transforms source code written in a programming language(the source language) into another computer language (the target language, often having a binary form known as object code). The most common reason for wanting to transform source code is to create an executable program.

Interpreter: In computer science, an interpreter normally means a computer program that executes, i.e. performs, instructions written in a programming language. An interpreter may be a program that either

1. executes the source code directly.2. translates source code into some efficient intermediate representation (code) and immediately executes this.

3. explicitly executes stored precompiled code[1] made by a compiler which is part of the interpreter system.

Virus: A computer virus is a computer program that can replicate itself and spread from one computer to another. The term "virus" is also commonly, but erroneously, used to refer to other types ofmalware, including but not limited to adware and spyware programs that do not have a reproductive ability.

Malware includes computer viruses, computer worms, Trojan horses, most rootkits, spyware, dishonest adware and other malicious or unwanted software, including true viruses.

Spam: Spam is the use of electronic messaging systems to send unsolicited bulk messages, especially advertising, indiscriminately. While the most widely recognized form of spam is e-mail spam, the term is applied to similar abuses in other media: instant messaging spam,Usenet newsgroup spam, Web search engine spam, spam in blogs, wiki spam, online classified ads spam, mobile phone messaging spam, Internet forum spam, junk fax transmissions, social networking spam, social spam, television advertising and file sharing network spam.

Antivirus Software: Antivirus or anti-virus software is software used to prevent, detect and remove malware (of all descriptions), such as: computer viruses, adware, backdoors, malicious BHOs, dialers, fraudtools,hijackers, keyloggers, malicious LSPs, rootkits, spyware, trojan horses and worms. Computer security, including protection from social engineering techniques, is commonly offered in products and services of antivirus software companies. This page discusses the software used for the prevention and removal of malware threats, rather than computer security implemented by software methods.

Browser: A web browser is a software application for retrieving, presenting, and traversing information resources on the World Wide Web. Aninformation resource is identified by a Uniform Resource Identifier (URI) and may be a web page, image, video, or other piece of content.

Web Site: A website, also written as Web site,[1] web site, or simply site,[2] is a set of related web pages containing content such as text, images, video,audio, etc. A website is hosted on at least one web server, accessible via a network such as the Internet or a private local area network through an Internet address known as a Uniform Resource Locator. All publicly accessible websites collectively constitute the World Wide Web.

A webpage is a document, typically written in plain text interspersed with formatting instructions of Hypertext Markup Language (HTML, XHTML).