Saturday, March 9, 2013

Comparison of Output Methods

Comparison of Output Methods

SUMMARY OF OUTPUT DEVICES

SUMMARY OF OUTPUT DEVICES

The following table (Fig 12) does not show a speed for plotters, which normally produce characters by drawing them. The speeds given are all in characters per second. Where the device does not produce individual characters the speed has been approximated; for example for a line printer it has been assumed that a whole line is printed each time, whereas for many applications much of each line would be left blank.

Device

Medium

Speed in c.p.s.

Magnetic disc unit

Magnetic disc

100 000 to 2000 000

Magnetic tape unit

Magnetic tape

150000

COM unit

Microfilm or microfiche

120000

Laser page printer

Paper

20000

Line printer

Paper

200 to 6000

Impact character printer

Paper

50 to 600

Television monitor

Cathode ray tube

60 to 2000

Plotter

Paper

Not applicable

Fig 12 Table of output devices

Note: There is no need for candidates to learn the speeds of devices. However, it is important to know which ones are fast and which are slow.

CHOICE OF OUTPUT METHOD

In buying or hiring output devices an installation has to consider:

1 Whether the devices purchased will cope with the needs of users for:

(a) Speed.

(b) Quality of output.

(c) Range of different types of output.

2 The cost of:

(a) The equipment.

(b) Running the devices-printers need paper but also bands or daisy wheels or ribbons, etc.

(c) Maintenance-some devices are less robust than others.

3 Adaptability-whether equipment can be adapted to fit in with future needs.

Many applications use a combination of output methods. For example:

1 A designer uses:

(a) The monitor of a graphical display unit while the design is being developed.

(b) A plotter to produce the finished designs.

2 A gas board uses the following while producing its customer accounts:

(a) Monitors on VDUs to check on individual accounts.

(b) A line printer to produce the bills.

(c) Microfiche for records of accounts which are more than 2 years old.