COMPUTER SYSTEM (CLASS - XI) (PART - 1)

COMPUTER SYSTEM

Chapter -1

INTRODUCTION

A computer is an electronic device, under the control of instructions stored in its memory that can accept data (input), process the data according to specified rules (Program), produce information (output), and store the information for future use.

Because of different units work as a single unit in computer for central objective, that’s why it is a system, i.e. computer system.

Data: Data are raw numbers or other finding which, by themselves, are of limited value.

Information: It is data that has been converted into a meaningful and useful context.

Any digital computers perform these functions in gross term.

1.      Take data as input

2.      Stores data/instructions

3.      Process those stored data

4.      Generate the output

5.      Control all above steps

Input Unit

A device through which data and programs from the outside world enter the computer system.

Output Unit

A device through which result stored in the computer memory are made available outside the computer system.

Input Devices Input devices can send data or information to a computer or another device. Keyboard: It is an input device which sends data in to the computer. The data send depends on the key pressed by the user.

Mouse: A mouse is a small handheld input device which controls a cursor in a graphical user interface. It can move and select text, files, folders etc. on our computer according to the user input.

Scanner: Scanner optically reads and document, file or image and then changes it into digital signal and sends to the computer.

OMR: optical mark recognition/ reader, is used to read marks on a document and send them to computer.

OCR: OCR stands for optical character Recognition, is an input device which reads printed text and sends that to computer.

MICR: Magnetic Ink Character Reader is an input device which generally finds application is banks to process cheques.

Microphone: it receives audio generated by some input source and sends the same to a computer.

Webcam: it sends the captured images to a computer.

Graphics Tablets: This input device is used to draw using hand.

Trackballs: an upside down mouse, encased within a socket. Is a cursor control device.

Barcode reader: It is used to read the barcode of various items and feed the same to computer.

Gamepad: Also known as joy pad is the input controller for video games.

Joystick: these input devices are used to control video games.