Information Technology

V.K.Muarleedharan

What is a Computer ?

• A computer is an electronic machine that process raw data

under

program

control to give meaningful information with speed and accuracy.

Characteristics of Computers:

Speed Accuracy High Storage Capacity Reliability Versatality Automation

Limitations of Computers :

• Lack of Commonsense• Inability to Correct• Dependence on human assistance

History of Computers :

• ‘Abacus’

–

The first known calculating machine (600 BC)

• Mechanical Calculator –

Blaisie

Pascal (1645), French Scientist and Mathematician.

• Multiplying Machine –

Gottfried Leibnitz

(1671), German Scientist.

History of Computers......cont....

• Jacquard’s Loom –

Mr. Joseph Mary Jacquard(1804), French Man.

• Difference Engine –

Charles Babbage (1813), English Scientist & Mathematician.

• Analytical Engine–

Charles Babbage (1863), English Scientist & Mathematician.

History of Computers......Cont..

• Charls

Babbage –

The father of Computers

• Punched Card Machine –

Dr. Herman Hollerith

(1890), U.S. Scientist.

• Harward

Mark I –

Howard Aiken (1937), in association with IBM

History of Computers......Cont..• ENIAC

(Electronic Numerical Integrator

and Calculator) –

Scientists of Harward University (1943), First Electronic

Computer• EDSAC (Electronic Delayed Storage and

Calculations) –

University of Manchester (1947)

• UNIVAC-I –

Sperry Rand Corporation , USA (1951)

History of Computers......Cont..• 1953 : IBM introduced IBM 650• 1961 : First commercial IC• 1968 : Founded Intel Corporation• 1972 : First 8 bit microprocessor by Intel• 1977 : Founded Apple Computer Company• 1968 : Founded Intel Corporation• ...............

Types of Computers

• Analog Computer• Digital Computer• Hybrid Computer

Analog Computer

“The variables are represented by continuous physical quantities”

Mainly used for Engineering and Scientific applications.

Speed but not accurate

Digital Computer

“works on discontineous

data (descrete

data). Convert the data in

to digits ”

Widely used for business and personal applications

Hybrid Computers

“utilise

the best qualities of both digital and analog computer. It is a combination of Digital and Analog

computers ”

Widely used in hospitals

Number System1. Decimal System : Consists of 10 numbers or symbols

(0,1,2,3,4,5,6,7,8&9) Base 10 system Positional Value system (value

depends upon position Eg

: 4672 –

(‘4’is the MSD & 2 is the LSD)

can be written as :(4X103)+ (6X102)+ (7X101)+ (2X100) = 4672

Number System.....cont..

2. Binary System: Consists of only 2 numbers or

symbols (0,1) Base 2 system Positional Value system Eg

: 11can be written as : 1 0 1 1

(1X23)+ (0X22)+ (1X21)+ (1X20) = 11

Number System.....cont..

3. Octal Number System: Consists of only 8 possible digits

(0,1,2,3,4,5,6&7)

Base 8 system 4. Hexa

Decimal Number System:

Consists of only 16 possible digits (0,1,2,3,4,5,6,7,8,9 +A,B, etc.)

Base 16 system

Bits & Bytes

1. Bits : Short form of ‘Binary Digits’ Numbers in a binary number system.2. Bytes : Combination of 8 Bits makes one

character (Byte)

Others Measures Kilobyte

(KB)

(210) =

1024

Megabyte (MB)

(220) =

1048576

Gigabyte

(GB)

(230) =

1073741824

Terabyte

(TB)

(240) =

1099511627776

Petaabyte

(PB)

(250) =

1125899906842624

Exabyte

(EB)

(260) =

Setabyte

(SB)

(270) =

Yotabyte

(YB)

(280) =

Data Representation Standards

BCD System (Binary Coded Decimal)

ASCII System (American Standard Code for Information Interchange)

EBCDIC System (Extended Binary Coded Decimal Interchange Code)

Boolean Algebra

Boolean constants and variables are allowed to have only two possible values that is ‘0 & 1’. This is used for getting best possible result.Three Basic Operations (Gates)

(1) OR, (2) AND & (3) NOT

Boolean Algebra......

OR Gate : Output Y=A+BAND Gate

: Output Y=A.B

NOT Gate (Single input) : Output Y=A

NOR Gate (Combination of NOT & OR): Output Y=A+B

NAND (Combination of NOT & AND) :

Out put Y = A.B

Boolean Algebra......

OR Gate : Output Y=A+B

AND Gate

: Output Y=A.B

Boolean Algebra......NOT Gate (Single input)

: Output Y=A

NOR Gate (Combination of NOT & OR): Output Y=A+B

NAND (Combination of NOT & AND) :

Out put Y = A.B

Structure of a Computer

ALU

CU Registers

Input Unit

Output Unit

Memory Unit

CPU

Terms

1.

CPU –

Central Processing Unit –

Most Important componant

-

Processing

operations are taken place here2.

ALU –

Arithmetic Logic Unit –

Logical

operations like calculations, comparisons are taken place here.

3.

CU (Control Unit) –

Control Unit directs and Co-ordinates all operations of a computer.

Memory UnitTwo types of Memory :

1. Primary Memory (Main Memory)

1. RAM (Random Access Memory)2. ROM (Read Only Memory)

a) PROM (Programmable ROM)b) EPROM (Erasable PROM)c) EEPROM (Electrically EPROM)

Memory Unit cont....1. Secondary Memory (Auxiliary Memory)

1. Magnetic Tape2. Magnetic Disk3. Floppy Disk (3.5”, 5.25”

& 8”)

4. Hard Disk (Metallic disk pack )5. Optical Disk6. Magnetic Bubble Memory (MBM)

Input & Output Devices

1. Input Devices : Used to enter data in to the computer.

1. Key Board2. Mouse3. Joystick4. Light Pen5. Magnetic Ink Character Reader

Input & Output Devices....cont...

6. Punched Card Reader7. OMR (Optical Mark Reader)8. Optical Character Reader (OCR)9. Bar Code Reader10. Voice Recognition system11. Scanner

Input & Output Devices

1. Output Devices : Used to supply the processed information to the users.

1. Visual Disply

Unit (VDU)Monitor

etc.2. Printer3. Plotter4. Voice Response devices (Speaker etc.)

Computer Hardware & Software

1. Hardware : All electronic, magnetic and mechanical components used in a computer system Eg

:

1. Key Board2. Mouse3. Mother board4. Hard Disk5. Removable drives etc.

Computer Hardware & Software

1. Software : Programs or sequence of instructions given to a computer to perform a particular task.

Types of Software :1. System Software :Programs needed to manage and support a

computer system and its information processisng activities.

Eg. Operating system, Programming Language Utility Programmes

etc.

Computer Hardware & Software

1. Application Software :Programs designed to accomplish a particular task. That is program for specific application only

Eg. Program for word processing, Spread sheet, Animation etc.

Operating System

Operating system : An interface between the User and the Hardware. OS controls all componants

of a computer system.

Functions of Operating System :1. Job Management2. Resource Management3. Data Management

Operating System.......

Types of Operating System :1. Single Program OS2. Multiprogram

OS

3. Time Sharing OS4. Real Time OS5. Multiprocessing OS

Operating System......

Popular Operating Systems :1. DOS (Disk Operating System)2. Windows (Version 1, 1.1......Vista)3. Linux4. UNIX -UNiplexed

Information Computing

System (UNICS)-1970s

5. Mac.

Operating System......

CUI

–

Character user interface (Support only characters)

(Eg. DOS)GUI

–

Graphic user interface (Graphical

supporting like sound, video, image etc.)(Eg. Windows, Linux etc.)

DMA - Direct Memory Access (less effort to OS)

Computer Languages

A standaised

communication technique for expressing instructions to a computer.

Used to develop programs or softwares.Types of Computer Languages :

1. Machine Languages2. Low level Languages (Assembly Languages)3. High level Languages

Computer Languages........

Machine Language : Written by using binary digits. High end technical knowledge is required.

Low level Languages (Assembly Languages) :Processed byan

assembler which translate the

assembly language in to machine language

High level Languages (Compiler Languages) :Closely resembles human language and make use of common mathematical notations.Eg

: COBOL, FORTRAN, BASIC Etc.

Data Processing

Data : unorganised

facts but able to be organised in to useful information.

Eg

: Name, Date of birth, Age, Mark etc.

Database : Collection of unorganised

facts

but able to be organised

in to useful information.Eg

: Student details, Employee details, etc.

Information : Manipulated or organised

data.

Data Processing.......

Data Base Management System (DBMS) : Interface between user and database. Programe

used for manipulating or processing the database to get meaningful informationEg

: ORACLE, MS-Access etc.

Database Architecture (Data Models) :

Hierarchical Model

Network Model

Relational Model (RDBMS)Relational Data Base Management System-very popular

Computer Network

Interconnected collection of independent computers

Types of Network:

Local Area Network (LAN)

Wide Area Network (WAN)

Metropolitan Area Network (MAN)

Personal Area Network (PAN)

3.

Network Topologies

Star Topology

Ring Topology

Bus Topology

Tree Topology

Hybrid Topology

3.