topic 1 revision homework

topic 1 revision homework

1. A computer system is an integrated collection of parts which work together for a common purpose. For a system to be useful it must produce something

2. Expert systems are computer systems designed to behave like a human expert. They have three computer parts • A knowledge base ( A database of facts or past results) • An inference engine (Software that makes judgments using the knowledge base) • An interface (To allow a human access to the system)

3. Embedded systems are computer systems that are part of a larger system. They are usually also control systems.

4. Control systems are systems which control machinery, rather than produce an output for humans to read or respond to.

5. a computer system must be reliable, tested andkeep to certain standards

   • Reliability: People become more dependent on computers so people have to trust there reliability. They are so reliable people do not give it much thought
     • This is the percentage of time the system is available to the user or customer but taking out any planned downtime perhaps for maintenance.
     • Stands for “Mean Time To Failure”. This is the average number of hours that the system runs for before something breaks. This tends to be a measure for hardware such as a server. For example if a hard disk fails on average 500 hours, then its MTTF figure is 500 hours.
     • a system needs to be reliable for safety reason for example if a system failed in an aircraft someone might die
   • Testing: Testing can be expensive so errors always make it to the system. Trying to fix these errors is called maintenance. Testers try to break the systems. Sometimes early versions are given to people so they can be tested in real life situations this is called beta testing.
   • Standards: A way people make computer systems more reliable is making them to certain standards
     • Proprietary standards These are standards that are owned by a company for example any software ran by windows must handle data in a certain way. Communicate with the operating system and work with a defined interface. The advantages are it will look and feel familiar and speed the learning to new users, work in a predictable way which will help reliability and be maintained by a certain country and will have different versions with minor updates free of charge
     • Industry standards are those that have been agreed across the computing industry. These normally relate to hardware and allow easy interconnection between devices. The universal Serial Bus (USB) has become the Industry standard
     • De facto standards are standards which just develop over time through common usage until they become the accepted way to make or do things. For example the layout of controls in a car is a de facto standard
     • Open standards refer to standards which are publicly available; to an extent the software developed under them can be modified by the user. Open standards are becoming increasingly popular advantage of software produced under open standards is that it is updated by a community of developers which means issues are addressed quickly and updates are released regularly for little or no cost. The software is often of high quality as the community of developers can act quickly to address and fix problems.

6. legal

   • The data protection act (1998) was created in order to protect people’s privacy as it is now very easy to copy and transmit data as well as to make judgement calls about individuals.
     • The computer misuse act (1990) makes it illegal to gain unauthorised access to computer systems or to modify the data stored in them.
     • ethical
       • these are not required by law
         • replacing humans with machined may be considered un ethical