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Input and Output Devices

 Input Devices

Input refers to the data or instructions which we feed  into a computer. Input devices are used to enrer data and information into a computer. The input unit converts the incoming data and instructions into a pattern of binary codes which is understood by a computer. Then it further supplies data to the processor for processing.

Some of the input devices are:

1. Keyboard: 

Keyboard is the one of the most important devices used to input data and instructions into a computer.
The standard computer keyboards typically contain 101 keys. There are mainly five types of keys on a keyboard:

types of keys



Keyboard

2. Mouse:

Mouse is the most commonly used input and pointing device that lets you select  and move items on the screen. The left mouse button is used  more, frequently than the right button. A single left  click selects an item while double-clicking on an item activates the application. The right-click  often displays a list  of commands on the screen.

Types of mouse:

1. Mechanical Mouse: 

This type of mouse has a metal or rubber ball on its lower side that can roll in all the directions. The screen pointer moves according to the movement of  the ball which is detected by the  mechanical sensors within the mouse.

2. Opto-Mechanical Mouse:

This type of mouse uses a mechanism similar to the mechanical  mouse. The only difference is that  it uses optical sensors to detect the movement of the ball.

3. Optical Mouse:

Optical mouse does not have any mechanical moving parts. An optical mouse is more efficient and expensive than the Mechanical and Opto-Mechanical mouse.



Scanner:

It is an input device that scans text, images and objects optically. The scanned data then converted  into a digital  image and displayed on the computer screen.

Types of Scanner:

1. Drum Scanner
2. Flatbed Scanner
3. Handheld Scanner

OCR(Optical Character Reader/Recognition):

OCR is an input device. It is used to read characters from a printed paper into the computer. The shape of the character is recognized by OCR through a light source in conjunction with photoelectric cells.

OMR (Optical Mark Reader/ Recognition):

OMR is an input device. It is a device for capturing data formed by dark and light marks on specific positions of the paper. The answer sheets are inserted into OMR for calculating the scores. It has a great speed and the marking is error free.

MICR(Magnetic Ink Character Reader/Recognition)

MICR is an input device. It  is primarily used by the banking industry to faciliate the processing of cheques. MICR codes can easily be read by humans.

Bar Code Reader

It is an input device used for reading bar codes present on various products. It is used in many stores for billing and inventory applications.


Bar code Reader

JoyStick: 

A joystick is an input device which allows the user to move an object on the screen. It is specially designed for gaming purpose. 


Joystick


Microphone:

It is an input device used to record an store voice or  any other sound into a computer. Microphone is commonly  used in video conferencing, speech recognition  programs, radio broadcasting, recording and sound amplifying systems.What is computer, Characteristics of compuer, How computer works



Microphone

LightPen:

It is an input device. It is a light- sensitive pointing device, commonly used to select or modify data on the screen. It is easy to use and helpful for programs like  computer aided design (CAD).

Light pen


Output Devices

The output unit is used for displaying or printing the processed data in a user readable form.

Some of the common output devices are:

Monitor:

Monitor is an output device. Monitor is also called Visual Display Unit (VDU). Monitor also displays the output on the screen. The  picture on  a monitor is made up of thousands of small coloured dots called pixels. 
( The output displays on the monitor is called  Soft-Copy)

The most common types of monitor are:

1. Cathode Ray Tube (CRT) monitors
2. Liquid Crystal Display (LCD) or Thin film Transistor (TFT) monitors.



CRT Monitor






LCD Monitor

Printers:

A printer is an output device. It is used for printing the output on a paper or any other prinable media. (The printed information on the paper is called the Hard Copy.)




Printer



Printers are of two types:

1. Impact Printer



2. Non-Impact Printer






Speakers:

Speakers are the output devices which are used to play sounds.  We can listen to music and various sound effects through them.


Speakers

Plotters:

Plotter is an output devie. It is used to print graphical plots on paper. (Plotters are different from printers.) 

Plotters are of two types:















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