Fundamentals of a computer system

Fundamentals of a computer system

1. computers are everywhere because they are versatile, cheap and small.

2. System

   • system-collection of parts that work together for a common purpose
   • for it to be useful, it needs to receive and process an input to produce and output.
     • there may be many inputs and outputs
   • they can interact with other systems and have sub-systems
   • interconnections with system are called interface
   • system boundary separate what is in a system from what is not
   • e.g solar system, railway system, respiratory system, network system
   • computer systems,
     • processing data and poducing information
     • electronic
       • fast
       • programmable
         • can be made into anything depending on the instructions given
     • dedicated
       • designed for one particular purpose
       • engine management systems
       • alarm clocks
     • general purpose
       • can be used for many purpose depending on what needs to be done
       • dedicated and embedded found in general purpose
       • PCs and mobile phones
     • embedded
       • computer system that forms part of an electronic device
       • dedicated systems found in other appliances are also embedded
       • fridges and washing machines.

3. why are computers important

   • they are used in many human activites
     • politics
       • vote system
       • tax payment
     • science
       • simulation
       • visualization
   • safety
     • controlling trains
     • autopilot
   • travel
     • GPS
     • flight booking
   • business
     • orders
     • stock control
   • retail
     • online ordering
     • self checkout
   • entertainment
     • MP3 players
     • DVDs
   • communication
     • smartphones
     • social networks
   • education
     • exam marking
     • smart boards

4. Reliability

   • as we become more dependant on computers we need to make sure that they are reliable
   • reliable systems can have serious problems
   • systems are created to take the workload of humans so we need to be able to understand them in order to keep them safe
   • unreliable systems result in loss of data
   • problems related to poor procedures or lack of understanding of the system
   • they do not do what is required and money is lost due to this

5. Testing

   • reliability is not easy to achieve and a lot of testing has to be done,
   • vital part of development
   • testing everything is impossible as it takes time and is expensive
     • need to be monitored all their life and needs to be imporved
   • changing a system once it is installed is called maintainence
   • it is not an attempt to show a system works, it is to reveal errors
     • may fail if unexpected code is put in
   • beta testing-users given an early version of the system so it can be tested in real life situations
   • alpha testing - carried out by the developer
   • tested against specification
     • many unreliable system cause problems due to error in the specification

6. Standards

   • make systems more reliable
   • help make sure that different computers can talk to each other
   • propreitery
     • owned by a company
     • e.g any software that runs under windows need to handle data in certain ways
     • look and feel familiar to users
     • work in predictable ways
     • maintained by one company and minor updates free of charge
   • industry standards
     • agreed across computing industry
     • easy interconection between deviices
     • e.g USB- can be connected to a variety of devices
   • De Facto
     • standars that have developed through common usage
     • allowing the movement of files more open
   • open standards
     • help develop system at no cost
     • publicly available and can be modified by the users

7. ethical consideration

   • what is right and wrong
   • not undertaking work beyond capability
   • people have a right degree of privacy in their lives however social networking have changed this.
   • journalist have invaded in people's lives
     • seen as ethical if it is for the right purpose and to gain interest
       • expose criminals, dishonest behaviour

8. Environmental consideration

   • energy
     • lots of energy used by computer
     • many wasted through inefficient generation fo heat which has to be removed from the equipment
     • air conditioning in centres to keep the heat low use more energy
     • energy is limited and expensive
   • Disposal
     • e-waste
     • computers contain toxin
     • toxin released to the environment
     • exported to countries with low standard of environmental protection
       • children pick waste metal to be recycled
         • save resources on a global scale
           • exposing children to danger