Lecture 2 Part I

Overview:
A computer system contains 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 which 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
? 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
2.1 Introduction
Interaction (with or without computer) is a process of information transfer. The variety of devices reflects the fact that there are many different types of data that may be entered into and obtained from a system, as there are many different users. In the early days, batch processing was common: a large mass of information was dumped into and processed by the computer. Nowadays, computers respond within milliseconds and computer systems are integrated in many different devices.
A typical computer system
Consider a typical computer setup as shown in Figure 1 There is the computer „box? itself, a keyboard, a mouse and a color screen.