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CHAPTER 2
the computer
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A computer system comprises various elements, each of which affects the user
of the system.
- Input devices for interactive use, allowing text entry, drawing and selection
from the screen:
- text entry: traditional keyboard, phone text entry, speech and handwriting
- pointing: principally the mouse, but also touchpad, stylus, and others
- 3D interaction devices
- Output display devices for interactive use:
- different types of screen mostly using some form of bitmap display
- large displays and situated displays for shared and public use
- digital paper may be usable in the near future
- Virtual reality systems and 3D visualization have special interaction and
display devices.
- Various devices in the physical world:
- physical controls and dedicated displays
- sound, smell and haptic feedback
- sensors for nearly everything including movement, temperature, bio-signs
- Paper output and input: the paperless office and the less-paper office:
- different types of printers and their characteristics, character styles
and fonts
- scanners and optical character recognition
- Memory:
- short-term memory: RAM
- long-term memory: magnetic and optical disks
- capacity limitations related to document and video storage
- access methods as they limit or help the user
- Processing:
- the effects when systems run too slow or too fast, the myth of the infinitely
fast machine
- limitations on processing speed
- networks and their impact on system performance.
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