6.3 Summary

This section examined how computers can be used to control machines. It used the household washing machine as a case study and explored how the microcomputer contained in such a machine is programmed to:

• provide an interface for the user to operate the machine;
  


• control the way the machine carries out the operations chosen by the user.
  

The washing machine case study also illustrated the necessity of building safety features into computer-controlled mechanisms.
Computers are also used to support selling goods and services via the web. A case study of a successful company showed what the information requirements for such a system are, and examined how two or more computers can cooperate as part of a distributed system to satisfy these requirements in a way that is secure.