Fundamentals of computer systems

Fundamentals of computer systems

1. Computer systems

   • They're everywhere because they're
     • versatile
     • cheap
     • small
   • computer
     • electronic programmable data processing machine
   • system
     • collection of parts that work together for some defined purpose
       • needs to receive and process inputs to produce outputs
         • some are dedicatesd
           • designed for a particular purpose
             • e.g log a mobile onto a network
           • some are general purpose
             • used for different reasons
               • e.g PCs
           • dedicated systems found in embedded systems
             • e.g linux kernal
               • k- lowest level of operating system that controls hardware
           • some are control systems
             • control machinery
               • don't produce an output for humans
               • e.g industrial robots
               • important in manufacturing
   • Computer system
     • collection of hardware and software that works together to achieve some data processing task
       • examples:
   • Outline of a system
     • system boundary
       • separates what is in a system from what is not (processor)
         • these boundaries can be called interfaces
   • embedded systems
     • a computer system that forms part of an electronic device
     • expert systems
       • computer systems designed to behave like a human expert
         • they have:
           • a knowledge base
             • an inference engine
               • an interface
                 • allow human user access
               • software that deducts using knowledge base
             • database of facts
   • management information systems
     • bring information together from all parts of an organisation
       • e.g school management information

2. why are computer systems important

   • improved quality in manufacturing- robots more accurate than humans
   • cheaper manufacturing automation allows 24/7 working
   • faster access to information
   • better decision making -organised facts
   • new ways of business - online shopping
     • orders, stock control
   • communication -emails,social network
   • education - exam marking, unlimited sources ,virtual learning
   • politics - voting , taxes
   • science -stimulations, visualisation
   • travel - gps system
   • safety - guiding aircrafts

3. Reliability

   • computers have central roles to our lives and we're becoming more dependent
     • if unreliable they can cause serious problems
     • e.g they control transport (airlines) and medical aspects
     • reliability is needed when new computer systems are commissioned
       • mistakes lead to
         • down time
         • expensive errors
         • data loss
         • compromised privacy
   • data integrity
     • data needs to be accurate and consistent throughout its life
     • stored data should reflect real world reality
     • faults
       • human errors when data entered
       • errors when data transmitted between computers
       • software bugs
       • viruses
       • hardware malfunctions
     • how to reduce
       • back up data
       • validation rules to prevent invalid data
       • error detection when transmitting data

4. Testing

   • reliability is improved by testing
     • shows where the weaknesses are
   • testing everything is impossible and very expensive
     • software is too complex
     • testing is expensive
     • testing is time consuming
   • once a system is released it's tested by users

5. Standards

   • refer to rules to make systems more reliable
     • Important because :
       • enable equipment from different manufacturers to work together
       • make learning systems easier
       • minimise waste
       • bring costs down
   • Propriety standards
     • owned by an organisation
     • ensure compatibility between company's products
       • easier for users to learn e.g apple products
         • work in a predictable way
     • reduce competition from rival products
     • not approved by an independent body
     • updates free of charge
   • Industry standards
     • standards agreed across the computing industry
     • relating to hardware
       • allow easy interconnection between devices
       • e.g Universal serial bus (USB)
         • standard way to connect devices to computer systems
   • De facto standards
     • standards that develop overtime due to common usage
     • ensure files and systems can be used by anyone
       • QWERTY keyboard layout
       • microsoft word
       • HTML
         • defining web pages
   • Open standards
     • standards that are publicly available
       • software developed under them can be modified by users
       • anyone with time and expertise can develop them
         • regular updates at minimal cost
       • not for profit
       • ensure access to resources is not dependent on:
         • a single application
         • a particular hardware form
     • e.g HTML HTTP TCP/IP
   • De jure standards
     • means by law
     • they've become so universally accepted
     • have to be adhered to or communication is impossible
       • e.g unicode TCP/IP

6. Ethical considerations

   • refers to what is morally right
   • on a personal level
     • British computer society
       • has ethical standards
   • privacy
     • social networking has made this harder
       • also media and journalism

7. Environmental considerations

   • E-waste
     • computers contain toxic materials
       • lead
       • flame retardants
       • cadmium
       • beryllium
       • they release dioxins
     • usually shipped to developing countries
       • very few safeguards
         • children become exposed
     • landfill
       • toxic chemicals enter soil
   • energy
     • wasted in inefficient generation of heat
     • air conditioning in data centres uses energy
     • supplies of energy are become more finite and expensive
     • reduction methods
       • solid state storage opposed to rotating disk drives
       • automatic standby
       • laying out equipment so it's cooled efficiently
       • modern screens

8. Legal consideratiosn

   • defined by law
     • data protection act 1998
       • protect people privacy
         • as it is easy to
           • copy data
           • transmit data
           • match data and make judgements about people
   • computer misuse act 1990
     • illegal to gain unauthorised access to computer systems
       • or modify data stored in them
   • cyber crime
     • difficult to police
       • internet crosses international boundaries

Images and files in the map