Peripheral Devices

Peripheral devices can be classified as Input Devices, Output Devices and Storage Devices.

Input Devices:- 

The Devices the help the user to enter the data and instructions to the computer are called input devices. Examples are Keyboard, Mouse, Light Pen, Joystick, Scanner Web Cam Etc.

Keyboard:- It is an Important and most frequently used input device.

The arrangement of keys on the keyboard is same like typewriter. The keys are classified as Alphabetic keys – A to Z, Number

Keys – 0 to 9, Symbolic Keys - !@#$ Etc., Function Keys F1 to F12,

Arrow Keys(Navigation Keys) – Up, Down, Right and Left Arrows. 6 Special Keys like Enter, Tab, Caps Lock, Shift, Ctrl, Ecs, Alt, Etc.

Mouse:- It is a Pointing Device and can be operated with One Hand. It has Three Buttons Viz. Left Right & Middle(Scroll).

Light Pen:- It is Connected to the Computer. When a switch provided on the Pen is pressed against the screen, the information written is transferred to the C.P.U. Normally it is used to draw figures on the screen.

Joystick:- peripheral input device that looks similar to a control device you would find on an arcade game at your local arcades. A computer joystick allows an individual to easily navigate an object in a game such as navigating a plane in a flight simulator.
 

Scanner:- Hardware input device that allows a user to take an image and/or text and convert it into a digital file, allowing the computer to read and/or display the scanned object. A scanner is commonly connected to a computer USB, Firewire, Parallel or SCSI port.

Web Cam:- A camera connected to a computer or server that allows anyone connected to the Internet to view still pictures or motion video of a user. The majority of webcam web sites are still pictures that are frequently refreshed every few seconds, minutes, hours, or days. However, there are some sites and personal pages that can supply streaming video for users with broadband.

Output Devices:- 

The Data, the processed information and the result are shown on the output device whenever required. Two type of Output Devices that are commonly used are Visual Display Unit (V.D.U.) & Printers.

1.V.D.U.:- This is the most commonly used output device. It gives a soft copy output i.e. the output shown vanishes if there is more information to be displayed or the power is switched off and hence can not be retained for longer duration. The types of V.D.U. are listed below.

a) Television Sets:- It can be connected to the regular television set with the help of radio frequency modulators built inside the computer. But it affects the eyesight and the clarity of output is also affected hence of popularly used there are two types of television sets viz. Colour & Monochrome.

b) Monitor:- Monitor is the popularly used output device which gives better quality of output than television. As television sets, monitors are also of two types- Monochrome and Colour

2. Printer:- Printer is the permanent output device. It prints the output on the paper that can be retained for a long duration even if disconnected from the computer; hence the output is called Hard Copy Output. Two basic types of Printer are listed below.

a) Impact Printer:- In Impact Printers, characters are printed by pressing a typeface (print mechanism) against an inked ribbon which makes an impression on the paper. E.g. Dot Matrix Printer, Daisy Wheel Printer.

b) Non-Impact Printer:- in non-impact printers, there is no contact between print mechanism and paper. E.g. Laser Printer- It uses a light beam to form an image on the paper using a Toner ink. The light beam become electricity charged and the charged area attracts the Toner ink particles that are deposited on the paper forming an image. The Image is made permanent on the paper using heat or pressure.

3.Backup Storage Device:- 

These are the Permanent storage devices, used to store data, instructions, information and the results in computer. The examples are Hard Disk, Compact Disk, DVD, External Hard Disk Etc.