Chapter 2

The Computer

2.1 Computer systems are constantly developing, and manufacturers keep encouraging us to buy the latest, fastest systems, with the newest designs of keyboards, screens, more memory and faster processors, and so on. Give examples of circumstances in which having the latest technology is advantageous, and give examples when it can cause difficulties.

answer

When raw computing power is at a premium, having the fastest computing power available is ideal - this is true for scientific applications, numerical modelling and analysis, and so on. Such increases in power can turn what were once batch jobs into interactive ones, allowing the user to explore and develop 'what if' scenarios that can lead to a better understanding of the underlying problems.

Developers of software usually benefit from having a faster design-code-compile-debug cycle, allowing them to produce their code more rapidly. However, this can cause problems too in that they become used to the capabilities of their machines and expect that all users will have similar resources. This can lead to large programs that perform ponderously on the more conventional machines that ordinary users have to work on.

2.2 Identify input and output devices that could benefit users with special needs.

answer

• Speech input - suitable for physically handicapped
• Speech output - suitable for the blind or those with other vision problems
• LCD screens - suitable for users with sub-optimal vision because they are clearer
• Touchscreens - for users with lower than usual hand-eye coordination
• Virtual Reality input and output - for immersive treatment of phobias
• Braille printer - hardcopy output for the blind
• ... continue ...

Worked exercises

• What input and output devices would you use for the following systems? For each, compare and contrast alternatives, and if appropriate indicate why the conventional keyboard, mouse and CRT screen may be less suitable. [page 87]
  • (a) portable word processor
  • (b) tourist information system
  • (c) tractor-mounted crop-spraying controller
  • (d) air traffic control system
  • (e) worldwide personal communications system
  • (f) digital cartographic system

• What is the basic architecture of a computer system? [page 95]

• How do you think new, fast, high-density memory devices and quick processors have influenced recent developments in HCI? Do they make systems any easier to use? Do they expand the range of applications of computer systems? [page 100]

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