Fundamentals of a computer system

Fundamentals of a computer system

1. What is a computer system?

   • Man made systems
     • Underground ntework
     • Cash machines
     • holiday booking forms
   • natural systems
     • Solar system
     • Digestive system
     • respiratory system
   • Computer systems are based on processing data and producing information and outputs. Computer systems are electric which means they are fast and reliable. Most importantly they are programmable which means they can be made to perform different jobs; depending on the instructions they are given.
   • All computer systems include: Input devices Output devices,Storage ,A processor, Software
   • There are six main types of computer systems. These are: • Dedicated systems • General purpose systems • Embedded systems • Control systems • Expert systems • Management Information systems

2. Reliability of computer system

   • Avail
     • This is the percentage of time the system is available to the user or customer but taking out any planned downtime perhaps for maintenance.
   • MTTF
     • 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.

3. Testing

   • Testing systems is a vital part of development and much time and effort should be devoted to this. Computer systems can have thousands of lines of code and limitless paths through it, for this reason reliability is hard to achieve. Testing every aspect of a system is expensive and virtually impossible. There will always be issues with systems so it is important that systems are monitored through their lives. This is known as system maintenance. System maintenance happens when changes are made to an already installed system. Testing is not an attempt to show a system works. Testing sets out to break the system to find where its weaknesses lie. When a system is tested many elements of it may work but some may fail when unexpected data is entered.
   • Most systems are released to a small group of users first so that the system can be tested under real life conditions. This is known as beta testing.Alpha testing is first carried out in-house by developers of the system. A system is tested against two key areas To identify weaknesses with the system in meeting specification To identify errors when coding. Issues with the system design are harder to fix than issues with coding.

4. Standards

   • Propietary standards
   • Industry standards
   • De facto standards
   • Open stadards

5. Environmental issues

   • Advantages • Helps find new ways to save the environment • Is used everywhere • Improve recycling • More people to work at home save environment by not travelling to work • Don’t need to print save trees • Used in solar panels which is renewable • Uses less and less power as they improve
   • Disadvantages • Uses electricity • Technological waste • E-waste • Mining to make computers • Expensive to produce • Damage environment • Power/batteries