INFORMATION TECHNOLOGY

DEFINITIONSComputer:A computer is an electronic machine that receives

input, stores and automatically processes data, and provides output in a useful format.

Data: Data is raw & unorganized facts and figures that

need to be processed.

DEFINITIONSInformation:When data is processed and organized so as to

make it useful and meaningful, it is called Information.

Information Technology:A term that refers to both the hardware and

software that is used to store, retrieve and manipulate information.

ADVANTAGES OF COMPUTERS Speed and accuracy of calculations and

processing. Save huge amounts of data. Economic in cost and time. Network communications.

COMPUTER GENERATIONS1st Generation (Vacuum Tubes)Very huge in size.Very expensive.Very low processing speed.Relied on the machine language to perform operations.

COMPUTER GENERATIONS2nd Generation (Transistors) Smaller Faster Cheaper

COMPUTER GENERATIONS3rd Generation (Integrated

Circuits) The speed and the efficiency of the

computers were increased.

COMPUTER GENERATIONS4th Generation (Present

Microprocessor)Most powerful.Can be linked together to form networks.Fastest and most efficient.

TYPES OF COMPUTER

SUPER COMPUTER Biggest and most powerful. Rare because of their cost and size. Used by companies like NASA.

MAINFRAME COMPUTER Great processing speed and data storage. Often connected to many individual PCs

with limited processing capabilities called dumb terminals.

Used in Banks, Airlines etc.

MINICOMPUTER A Midsize Computer not very common

now. Minimized in size and power. Can connect up to 200 users at a time.

MICROCOMPUTER Also called Personal Computer (PC) Small enough to fit on top of a desk, which

can be used by one user at a time. Used in homes, schools etc.

WORKSTATION COMPUTER High-end microcomputer. Used by one person at a time. Commonly connected to a local area

network.

CONTROL COMPUTER Used for controlling operations in

industrial, medical devices and travel media like planes and cars

Also used to alert in any dangerous case.

PARTS OF A PERSONAL COMPUTER

Computer

Hardware Software

DEFINITIONSHardware:The physical parts of a computer which you

can see and touch.

Hardware

1) Input

Devices

2 )Output Devices

3)

Processing

Unit

4) Memory Unit

5) Storage Devices

HARDWARE1) Input Devices: Devices used to translate the data into a form that the computer can process.

a) Keyboard

It is a board containing the keys of letters, numbers and some functions which allows you to type information into the computer.

b) Mouse

A small hand-held device used to point, select, click on items and to drag and drop items from one place to another.

c) Scanner

It allows you to scan pictures, text and images and save it to your computer in a digital form.

d) Bar Code ReaderPhotoelectric scanners that translate the bar code symbols into digital form.

e) Joystick

Small hand-lever that can be moved in any directions to control movement on the screen.

It can be used for playing games.

HARDWARE2) Output Devices: Devices used to translate the processed information into a form that humans can understand.

a) Monitor (computer screen)

It displays the text, information and pictures.

They are different in (Size and Resolution)

b) Printer

It produces a hard copy of the material you are working on.

Types:1) Laser Printer 2) Ink-jet Printers

c) Plotters

It is similar to a printer but allows you to print larger images.

d) Speakers / Headphone

They are used to output voice from a computer

NOTE:Some devices can be used as both Input and

output devices at the same time such asTouch Screen:It receives input from the touch of a finger.

HARDWARE3) Processing unit(CENTRAL PROCESSING UNIT) The most important part of a computer system. Referred to as the brain of the computer. Determines the speed of computer which is measured in MHz or GHz.

1 GHz= 1000 MHz

CPU (Central Processing Unit )CPU consists of: CU (Control Unit): It tells the

computer system how to carry out program instructions from the memory. It controls and coordinates all activities of the computer.

ALU (Arithmetic and Logic Unit): It performs mathematical and logical operations

HARDWARE

4) Memory unit Memor

yRAM ROM

RAM (Random Access Memory)

The operating system is loaded into the RAM when you switch on your computer.

Used to store applications that you are currently working with.

It is temporary (volatile).

ROM (Read Only Memory)

It has special programs which are built-in when you buy the computer.

Used to store control programs. It is permanent (non-volatile).

HARDWARE5) Storage Devices: Hardware devices which are used to record

and store data.

1) INTERNAL STORAGEHARD DISK

It is the most important storage media in the computer.

It stores operating system and programs.

2) EXTERNAL STORAGE

A compact and easy-to-use device for transferring data between computers.

a) Flash Memory

b) CD (Compact Disk)

An optical disk which uses laser to read information.

It has 750 MB capacity.

c) DVD (Digital Versatile Disk)

A high-density video disc that stores large amounts of data, especially high-resolution audio-visual material like movies, encyclopedia etc.

The capacity is up to 17 GB.

DISK AND MEMORY CAPACITY

The first level of storage is called bit (the bit is referred to a binary number 0 or 1).

Byte = 8 bits.Kilo Byte (KB) = 1024 bytes.Mega Byte (MB) = 1024 KB.Giga Byte (GB) = 1024 MB.Tera Byte (TB) = 1024 GB.

COMPUTER PERFORMANCE1. The speed of the processor.2. The capacity of RAM.3. The capacity and the speed of

the Hard disk.

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