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GCSE Computing

GCSE Computing . Lesson 4. Computer systems What is a system?. Inputs. Outputs. Processes. System boundary. 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.

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GCSE Computing

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  1. GCSE Computing Lesson 4

  2. Computer systems What is a system? Inputs Outputs 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, H2O 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 • Answer questions on page 17. No writing is required for the Extension question 4.

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