OUTPUT DEVICES:  There are the physical components of a computer used to obtain results from computer after processing. There devices convert data from machine-readable format into human-readable format.
(a) Monitor (b) Printer (c) Plotter (d) Speaker (e) Projector (f) Microfilm, etc.

This is an output device that displays the result of processing on the screen. It looks like a television set and it’s usually called a Visual Display Unit or simply the Screen. The output obtained from a monitor is called the softcopy since this output can only be seen.

Monitor can be classified in two categories. These are based on
(1) Shape
(2) The number of colour it displays based on the shape. There are two types
(3) (a) CRT (Cathode Ray Tube) monitor: There are very bulky but are usually less expensive than the LCD monitor. They are more precise in colour.
(b) LCD (Liquid Crystal Display) Monitor: These have flat screen and are lighter in weight but more expensive.

They are commonly used in laptop, notebooks, palmtops as well as desktop computers.
Based on the number of colours. There are three (3) types:
(i) Monochrome Monitor
(ii) Gray-scale
(iii) Polychrome or colour monitor

(i) Monochrome Monitor: This monitor displays one colour at the background and one colour at the foreground. The colour can be black and white, green and black or amber and black.
(ii) Gray-scale Monitor: This is a special types of monochrome monitor capable of displaying different shade of gray.

(iii) Colour Monitor: This monitor displays 16 to about 1 million different colours. They are sometimes called RGB monitors because they accept three separate signals – Red, Green and Blue.

The different types of colour monitors are:

(a) Colour Graphics Adapter (CGA) which displays 4 colours
(b) Enhanced Graphics Adapter (EGA) which supports 16 colours.
(c) Video Graphics Adapter (VGA) which supports 16 to 256 colours.
(d) Super Video Graphic Adapter (SVGA) which supports 256 and more colours.

A printer is an output device that produces output on paper and other similar printing media. The output of a printer is called hardcopy.

Types of printers

(1) Impact Printers and (2) Non-Impact Printers.

(1) Impact Printer
These are the printers capable of creating images by using some mechanism to physically press an inked ribbon against the page, causing the ink to be deposited on the page in the desired shape. These are noisy printers.
Examples are: (a) Daisy wheel (b) Dot-matrix (c) Band Printer (d) Golf Ball Printer (e) Chain Printers, etc
(2) Non-Impact Printers
These are printers that operate without direct physical contact between the printing mechanism and the paper. They spray ink on paper or use photo technology in printing images. Examples are as follows (a) Inkjet printer (b) Thermal printers (c) Laser printer (d) Spark jet, etc. Non-impact printer is not as noisy as impact printer.
Other printer types are: (i) Character printer (ii) Line printer (iii) page printer.

These are output devices that prints vector graphics. It draws pictures on paper using a pen. Plotters are used in applications such as computer Aided Design. They are used for producing computer graphical output in form of graphs. E.g. printing designs of ships and machines, plans for building etc.
They are also used in scientific researches, engineering and management information system (MIS).
Examples of plotter
(a) Electrostatic Plotter
(b) Cutting plotter
(c) Pen Plotter, etc.

These are also called sound blasters. They are used to obtain sound or audio output from the computer. Speakers are connected to sound card or sound adapter on the motherboard. The sound card translates digital information to sound and back to digital information.
To play sound or audio, the sound card receives digital information from a stored file and turns it into an electrical signal, this signal is then sent to the speaker which produces sound.

This is an output device that projects image onto a surface or a projection screen. It is used to show the result from the computer on a large flat screen. A projector is usually used in meetings, workshops, seminars, conferences or to make presentations because it allow large image to be shown on the screen which the display is available to a large audience. Projector can be used in place of monitor.

This is used to store voluminous output that will require too much space if stored normally such output are stored on film by the processor in a reduced format. The microfilm machine or reader can then be used to later search for the required information and print it out.

Types of Microfilm
(a) Silver Halide film
(b) Vesicular film


  • State the difference between printer and plotter
  • Explain the function of a speaker
  • What is the major use of a microfilm
  • State the difference between a monitor and a speaker

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Samuel Okeke

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