Computer Introduction

Definition of computer:-

Computer introduction:

A computer is general purpose electronic machine invented to help people to solve problem. Computer must be programmed by human beings to perform various tasks. Various programming techniques are used for problem solving on computer.

In other words:

A computer is programmable electronics device that takes data, perform instructed arithmetic and logic operations, and gives output. The computer as input is called data and output recieved is called information.

Basic computer, it working:

INTRODUCTION:-

A computer is general purpose electronic machine invented to help people to solve problem. Computer must be programmed by human beings to perform various tasks. Various programming techniques are used for problem solving on computer.

short keys:

input/output devices:

Following are few of the important input devices which are used in a computer:

Keyboard Mouse , Joy Stick,  Light pen,  Track Ball,  Scanner,  Graphic Tablet,  Microphone,  Magnetic Ink Card Reader MICR,  Optical Character Reader OCR,  Bar Code Reader,  Optical Mark Reader OMR.

Keyboard :-

Keyboard is the most common and very popular input device which helps in inputting data to the computer. The layout of the keyboard is like that of traditional typewriter, although there are some additional keys provided for performing additional functions.

 Keyboards are of two sizes 84 keys or 101/102 keys, but now keyboards with 104 keys or 108 keys are also available for Windows and Internet.

The keys on the keyboard are as follows:

Keys                             Description

Typing Keys                These keys include the letter keys A − Z and digit keys 0 – 9 which generally

                                     give same layout as that of type writers.

Numeric Keypad             It is used to enter numeric data or cursor movement. Generally, it consists of

                                         a set of 17 keys that are laid out in the same configuration used by most

                                         adding machines and calculators.

Function Keys                 The twelve function keys are present on the keyboard which are arranged in a

                                         row at the top of the keyboard. Each function key has unique meaning and is

                                         used for some specific purpose.

Control keys                    These keys provide cursor and screen control. It includes four directional

                                         arrow keys. Control keys also include Home, End, Insert, Delete, Page Up,

                                         Page Down, ControlCtrl, AlternateAlt, EscapeEsc.

Special PurposeKeys       Keyboard also contains some special purpose keys such as Enter, Shift, Caps

                                         Lock, Num Lock, Space bar, Tab, and Print Screen

Mouse:-

 Mouse is most popular pointing device. It is a very famous cursor-control device having a small palm size box with a round ball at its base which senses the movement of mouse and sends corresponding signals to CPU when the mouse buttons are pressed.

Generally it has two buttons called left and right button and a wheel is present between the buttons. Mouse can be used to control the position of cursor on screen, but it cannot be used to enter text into the computer.

Advantages:-

 Easy to use

Not very expensive

 Moves the cursor faster than the arrow keys of keyboard.

Joystick:-

Joystick is also a pointing device which is used to move cursor position on a monitor screen. It is a stick having a spherical ball at its both lower and upper ends. The lower spherical ball moves in a socket. The joystick can be moved in all four directions. The function of joystick is similar to that of a mouse. It is mainly used in Computer Aided Designing CAD and playing computer games.

Light:-

 Pen Light pen is a pointing device which is similar to a pen. It is used to select a displayed menu item or draw pictures on the monitor screen. It consists of a photocell and an optical system placed in a small tube. When the tip of a light pen is moved over the monitor screen and pen button is pressed, its photocell sensing element detects the screen location and sends the corresponding signal to the CPU

.Track Ball:-

Track ball is an input device that is mostly used in notebook or laptop computer, instead of a mouse. This is a ball which is half inserted and by moving fingers on ball, pointer can be moved. Since the whole device is not moved, a track ball requires less space than a mouse. A track ball comes in various shapes like a ball, a button and a square.

 Scanner:-

 Scanner is an input device which works more like a photocopy machine. It is used when some information is available on a paper and it is to be transferred to the hard disc of the computer for further manipulation. Scanner captures images from the source which are then converted into the digital form that can be stored on the disc. These images can be edited before they are printed.

Digitizer:-

 Digitizer is an input device which converts analog information into digital form. Digitizer can convert a signal from the television or camera into a series of numbers that could be stored in a computer. They can be used by the computer to create a picture of whatever the camera had been pointed at. Digitizer is also known as Tablet or Graphics Tablet because it converts graphics and pictorial data into binary inputs. A graphic tablet as digitizer is used for doing fine works of drawing and image manipulation applications.

 Microphone:-

 Microphone is an input device to input sound that is then stored in digital form. The microphone is used for various applications like adding sound to a multimedia presentation or for mixing music.

 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 bank's code number and cheque number are printed on the cheques with a special type of ink that contains particles of magnetic material that are machine readable. This reading process is called Magnetic Ink Character Recognition MICR. 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 Readers:-

 Bar 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. It may be a hand held scanner or may be embedded in a stationary scanner. Bar Code Reader scans a bar code image, converts it into an alphanumeric value which is then fed to the computer to which bar code reader is connected.

inside system unit:

                                          Computer shortcut key