Input and Output Devices

Input and Output Devices

A wider variety of input and output devices are used for communication with the computer. We will describe some commonly used input and output devices.

Keyboard:
 
Keyboard is the most commonly used input devices. A keyboard is used to enter information and instruction in to a computer. It consists of a set of keys similar to that used in a typewriter. It has some special keys like Ctrl, All, Esc, return, function keys etc. in addition to those in a typewriter. These keys have special functions. The layout is similar to that of a typewriter.

Mouse:

Mouse is also an input device which provides a keyboard for entry of instruction. It is a hand held printing devices which can be used to move the cursor on the screen of VDU and required action is chosen by processing a button on the back of the mouse.

Microphone:

A microphone is used with sound to record speech and other sounds.
 
Scanner:

A scanner reads graphics and text in to a computer; scanners are available in various sizes.

VDU (Monitor):

Video Display Unit is the most commonly used output device. It is similar to a Television which uses Cathode Ray Tub (CRT) for display. Information (text and images) can be quickly displayed on the screen of a VDU. Several types of VDU’s are used in a computer e.g. CGA, VGA, EGA, etc. These are available with both colour black and white screen. The size of a monitor is measured diagonally across the screen. A screen of such VDU generally contains 24 lines of text with 80 characters in each line.

Printers:

Printer is an output device which facilitates printing of the output on paper, one line of character at a time. Varieties of printers are available with various printing speeds and quality of printing. Some are briefed below:

Plotters:

Plotters are useful for producing high quality line graphs, maps and plans. They are available in many sizes. A plotters draws lines on paper using pens. Some models can produce coloured output by selecting coloured pens from a pen holder. The required pen is picked up from the stand and moved on the paper under software control. A combination of movements creates pictures and graphs. It is a slow device.

Speakers:

Speakers are used to listen sounds created by a sound card in a computer.