Peripheral Devices

Pheripheral

A computer peripheral is a device that is connected to a computer but is not part of the core computer architecture.
They are mainly divided into two types

                                                           1. Input Devices

                                                           2. Output Devices

1. Input Devices

	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
	Mouse Mouse is most popular pointing device.  It is a very famous cursor-control which senses the movement of mouse and sends corresponding signals to CPU when the mouse buttons are pressed.
	Joy stick Joystick is also a pointing device which is used to move cursor position on a monitor screen. 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.
	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.
	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.
	Digitizer Digitizer is an input device which converts analog information into digital form.  Digitizer is also known as Tablet or Graphics Tablet because it converts graphics and pictorial data into binary inputs.
	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.
	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.
	Barcode Reader It is a device used for reading bar coded data (data in form of light and dark lines). It scans a bar code image, converts it into an alphanumeric value which is then fed to the computer.
	Optical Mark Reader(OMR) OMR is a special type of optical scanner used to recognize the type of mark made by pen or pencil. It is specially used for checking the answer sheets of examinations having multiple choice questions.

2. Output Devices

• Monitors
• Graphic Plotter
• Printer

Monitors

• Monitors, commonly called as Visual Display Unit (VDU), are the main output device of a computer.
• It forms images from tiny dots, called pixels that are arranged in a rectangular form.

There are two kinds of viewing screen used for monitors.

• Cathode-Ray Tube (CRT)
• Flat- Panel Display

Cathode Ray Tube(CRT) Monitor

• The CRT display is made up of small picture elements called pixels.
• A finite number of characters can be displayed on a screen at once.

Disadvantages

• Large in Size
• High power consumption

Flat Panel Display Monitor

The flat-panel display refers to a class of video devices that have reduced volume, weight and power requirement in comparison to the CRT.

The flat-panel display is divided into two categories:

• Emissive Displays - The emissive displays are devices that convert electrical energy into light. Example are plasma panel and LED(Light-Emitting Diodes).
• Non-Emissive Displays - The Non-emissive displays use optical effects to convert sunlight or light from some other source into graphics patterns. Example is LCD(Liquid-Crystal Device).

Printers

Printer is an output device, which is used to print information on paper.

	Impact Printers	Non Impact Printers
Cost	Less	More
Speed	Less	More
Noise	More	Less
Quality	Poor	High
Other Lang.	can be printed	can be printed
Colour	Not possible	Possible
Types	Dot Matrix, Daisy Wheel, Line Printer(Drum and Chain)	Laser, Inkjet