1. GCSE COMPUTING Lesson 4

2. Computer systems What is a system? InputsOutputs Processes System boundary

3. Computer systems Examples of a system – can you identify what they are? Passengers, electrical energy Journeys Train movements Food, oxygen Energy, CO, H 2 O Oxidation Enquiry, deposit Tickets, reservations Search, Make booking

4. Computer systems  Computer systems are based on processing data and producing information  They are programmable.  Found in most electronic gadgets  Usually made of Input/Output devices, storage, a processor and software  Some computer systems are dedicated. In electronic gadgets they are known as embedded systems.  Controlling focus and shutter speed of a camera  Car cruise control  Logging a mobile phone onto a network  Guiding a robot vacuum cleaner around obstacles.  Some computer systems are general purpose.

5. Computer systems  Involved in most human activities – see list on page 10  Reliability  Need to trust computers, need them to be reliable.  Unreliable computers  can have lethal consequences in some situations. Can you think of any?  Loss or theft of data – inadequate security systems  Don’t perform the function they were programmed for.

6. Computer systems  Testing  Some programs have millions of lines of code.  Testing is a vital part of development.  Sometimes impossible and expensive to test everything.  So monitoring for the life of the system is important.  Testing is carried out to try and break the system, to show where its weaknesses are.  Testing may be done by users – this is called beta testing. (Alpha testing is done by the developers)  Testing is done against the specification.  Some systems are flawed because the specification is bad.

7. Computer systems  Standards  Benchmarks and procedures to adhere to, to increase the reliability of the system.  Common standards help with compatibility issues between computer systems  Proprietary Standards  Company standards – defined by the software company itself – e.g. Windows adhering to standards set by Microsoft and Flash with Adobe.  Insistence of company standards will:  Provide a familiar look and feel to the systems  Make them work in a predicable way  Allow maintenance through one company.

8. Computer systems  Standards  Industry Standards  Usually relate to hardware such as the USB standard for interconnectivity between devices.  De Facto Standards  Standards that have developed through common usage  Car layouts  HTML  PDF (Originally a proprietary standard from Adobe then given to the International Organisation for Standardisation)  Microsoft Word.doc formats

9. Computer systems  Standards  Open Standards  Standards that are publically available and usually developed through open source software.  Updated via a community of developers, usually free  Usually high quality  No one to blame if errors  Examples  HTML  TCP/IP  C#  Firefox  Libre Office  Android  Linux  Apache Web Server  Moodle  Python

10. Computer systems  Ethics  Codes of ethics in the computing world  BCS – British Computing Society  Sets ethical standards that computing professionals should adhere to.  E.g. working beyond your capability  Injuring others  Taking bribes  Privacy issues  Social media.  Journalistic invasion.

11. Computer systems  Environmental Considerations  Energy  Computers use energy  Data centres use a lot.  More energy than the aviation industry by 2014  Inefficient generation of heat that has to be removed  Air conditioning for machines  Disposal  E-waste  Computers contain toxic and carcinogenic components  Classified as hazardous waste  Sent to landfill sites – toxic materials can escape into the environment  Sent to third world countries with poor environmental policies. Danger to children and people trying to salvage materials

12. Computer systems  Legal Constraints  Data Protection Act 1998  Computer Misuse Act 1990

13. Computer systems  Task Using Publisher, Create a leaflet on one of the following topics. Reliability The importance of testing Ethics The Data Protection Act The Computer Misuse Act Standards