Information Technology

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),

Computer

First Electronic

• 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 System 1. 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  Megabyte  Gigabyte  Terabyte  Petaabyte  Exabyte  Setabyte  Yotabyte

(KB) (MB) (GB) (TB) (PB) (EB) (SB) (YB)

(210) = 1024 (220) = 1048576 (230) = 1073741824 (240) = 1099511627776 (250) = 1125899906842624 (260) = (270) = (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+B AND 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 CPU

ALU Input Unit

Output Unit

CU

Registers

Memory Unit

Terms 1. CPU – Central Processing Unit – Most Important componant - Processing operations are taken place here 2. 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 Unit Two 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 Tape 2. Magnetic Disk 3. Floppy Disk (3.5”, 5.25” & 8”) 4. Hard Disk (Metallic disk pack ) 5. Optical Disk 6. Magnetic Bubble Memory (MBM)

Input & Output Devices 1. Input Devices : Used to enter data in to the computer. 1. Key Board 2. Mouse 3. Joystick 4. Light Pen 5. Magnetic Ink Character Reader

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

6. Punched Card Reader 7. OMR (Optical Mark Reader) 8. Optical Character Reader (OCR) 9. Bar Code Reader 10. Voice Recognition system 11. Scanner

Input & Output Devices 1. Output Devices : Used to supply the processed information to the users. 1. Visual Disply Unit (VDU)Monitor etc. 2. Printer 3. Plotter 4. Voice Response devices (Speaker etc.)

Computer Hardware & Software 1. Hardware : All electronic, magnetic and mechanical components used in a computer system Eg : 1. Key Board 2. Mouse 3. Mother board 4. Hard Disk 5. 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 Management 2. Resource Management 3. Data Management

Operating System....... Types of Operating System : 1. Single Program OS 2. Multiprogram OS 3. Time Sharing OS 4. Real Time OS 5. Multiprocessing OS

Operating System...... Popular Operating Systems : 1. DOS (Disk Operating System) 2. Windows (Version 1, 1.1......Vista) 3. Linux 4. 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 Languages 2. 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 information Eg : 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.