Output Devices : Summary

1. 

An output device takes data from the computer and converts this into information in a form which is normally understandable by humans.

 
2. Soft copy output devices produce temporary output, whereas hard copy output devices produce permanent output.
 
3. There are two types of Visual Display Unit (VDU). They are desktop monitors which use a cathode ray tube like a television and liquid crystal displays. Important factors when selecting a VDU are size, resolution and cost.
 
4. Printers or plotters are hard copy output devices. Printers are either impact printers (produce output by striking a ribbon) or non-impact printers.
 
5. The table below compares the main types of printers and plotters.

Comparisons of Printers and Plotters
Type Cost Speed Quality Graphics Paper Colour Fonts
Dot Matrix £100 + 300 cps Poor Yes Continuous or Sheets Poor Lots with Software
Laser £80-£15000 Mainly £600 8-100 ppm Excellent Yes Sheets Very Expensive Lots
Ink Jet £30+ 8-24 ppm Excellent Yes Sheets Yes Lots
Thermal Built into other devices (cheap). 3 ppm Poor Yes Roll of Special Paper No Lots
Plotter £700-£5000+ Very Slow Excellent Yes Large Sheets e.g. A4-A0 Yes Draw as Graphics

Abbreviations : PPM = pages per minute, CPS = characters per second

 
6. Speakers can produce sound output such as music or synthesised speech.
 
7. MIDI instruments can be controlled by a computer. Music can be played back through up to 16 instruments simultaneously.
 
8.  Microfilm is a special type of photographic film which can store images at greatly reduced sizes (about 1/50th of the original size). In the past documents were stored on microfilm but it is rarely used now.
 
9. MIDI instruments can be controlled by a computer. Music can be played back through up to 16 instruments simultaneously.
 
10. A wide variety of control devices such as motors, lights and pumps can be switched on and off by a computer.

(C) P Meakin 2004