controlled by a mouse. The screen can be divided into different areas which can have different things in them; these areas are called windows. Put the four elements (windows, icons, mouse, pointer) together and you get WIMP. Graphical user interfaces are sometimes called WIMPs. Pointing using a mouse and clicking on pictures is simple to do and requires little IT knowledge, so a GUI is an interface that can be used by a young child or by someone who knows nothing of computers. A command-line interface (CLI) is also an interface for communicating with a computer (Figure 1.9). However, this time you have to type in specific commands to tell the computer what to do. This is far more difficult to use for two main reasons: • the user must know all the commands; • the user must be careful not to make any typing errors – otherwise the computer will not be able to understand the commands and carry them out.
Questions 4 Many other types of interface can be used on computer systems. a Find out about menu-based interfaces and form-based interfaces. For a menu-based interface, find an information system at a local train station or bank. For a formbased interface, look at a typical website for booking a hotel room: http://www.ichotelsgroup.com/ is a good example. b For each one try to find some uses and explain why they are used.
5 Find out what experience members of the class have of different interfaces. What types of user interfaces are used by different people in school? Why do they each need the type of interface which they use?
Extension
• •
Try to find out about some more types of interface. What, for example, is a ‘natural language’ interface? Are the type of user and the job that is to be done the only factors dictating what a computer interface
•
will look like? A washing machine uses a computer processor to control the wash cycle. What does the user interface look like? Why is it not a GUI?
Figure 1.9 A command-line interface.
Command-line interfaces are used by people like technicians looking after computer systems. The technicians know the commands and are able in this way to access the whole of the system. However, someone using a GUI can only get to places on the system that they have been given icons for.
SAQ 5 a What is an operating system (OS)? b Describe the features of i
a graphical user interface
ii a command-line interface.
1f,g
Types of computer and their development over time People have been building calculating devices for centuries. In the 20th century, electronic computers became possible. As you saw at the start of this module, one of the first, Colossus, was invented in the early 1940s by a team of code breakers working at Bletchley Park in the UK. They were trying to decode messages sent by German forces during World War II. Although Colossus worked far faster than any people could do, compared with computers today it was very slow. It was massive, filling a room (Figure 1.1), and very
Types and components of computer systems 7