Fundamentals of Computer Systems

Fundamentals of Computer Systems

1. Basic Computer System Model

   • Input, process, output (storage)
     • Input - getting data from the real world
     • Output - Presenting the data, possibly via an output device

2. Importance of Computers

   • Increasingly dependent on computer systems
     • Could be health and safety implications if it goes wrong
       • Motorways, hospitals
     • School, work, entertainment, ecommerce
   • Measure reliability
     • Availability = % of time available
     • Mean Time Between failures (MTBF) = length of time between system failures
   • Protecting against failure
     • Hardware redundancy is having more than one critical component , i.e. aircraft have triple redundancy in case of failure
     • Data is most at risk
     • Disaster recovery plans can be put in place enabling companies to switch over to entirely new systems with all their own data within hours

3. Professional Standards

   • In system development
     • Waterfall model
       • Identify problem, analysis, design, code & test, evaluation, maintenance
     • (RAID) Rapid Application Software
       • Starts with a prototype that is developed gradually into a full solution
   • In coding
     • De facto - factors that are considered good practice
       • Comments in code to define purpose
       • Indents to clearly show what is inside a loop
     • Using professional standards means that other people work is not plagiarised. This is referred to as intellectual property and this is protected by the Copyright, Designs and Patents Act
     • Some developers choose not to protect their work and create open source code
   • In documents
     • Use recognised symbols/ words
       • Flow chart symbols
       • Logic diagrams, AND, OR, NOT
     • Enables teams to develop systems and understand each other
     • Enables employees to move between companies as standards are applied across industry
     • Maintain and edit someone else's code

4. Considerations

   • Legal Considerations
     • Data protection Act - anyone that stores personal data must keep it secure
     • Health & safety at Work Act makes employers responsible for their staff
     • The Copyright, Designs & Patents Act makes it illegal to use software without buying the appropriate licence
   • Ethical Considerations
     • Is it fair that some people cannot afford computers?
     • Are countries like India being exploited as a source of cheap labour
     • Should companies use local programmers and call centres
   • Environmental Considerations
     • Carbon footprint
       • Work from home/ drive less
       • manufacturing computers