Computer systems
- Created by: Hollie Wickens
- Created on: 30-03-14 15:10
View mindmap
- Computer systems
- Systems
- A system is a collection of parts that work together for a common purpose
- For a system to be useful, it must produce something - an output
- It needs to receive and process inputs in order to produce outputs
- Systems often interact with other systems
- Systems may be made from many sub-systems
- Interconnections between systems are called interfaces
- A computer system is a system that is able to take a set off inputs, process them and create a set of outputs
- This is done by a combination of hardware and software
- For a system to be useful, it must produce something - an output
- Most electric and electronic devices rely on computer systems
- For example, a car has over 50 processors that control most of its functions
- Instead of lots of power cables, control signals are passed along a bus to the actuator which carries out the job such as raising the window
- Most computer systems in electronic devices are dedicated, which means that they are designed specifically for that one job
- They are called embedded systems because they are part of another device
- Other computer systems are general purpose, meaning they can be used for different reasons according to what work needs to be done
- PCs are general purpose, and can run word processors, browse the internet, and play music and movies
- For example, a car has over 50 processors that control most of its functions
- The kernel is the lowest level of an operating system that controls the hardware
- A system is a collection of parts that work together for a common purpose
- Importance
- Computer systems are involved in most human activities
- Safety - guiding aircraft, controlling trains, supporting signalling systems, monitoring patient body signs
- Travel - smart phone apps, GPS systems, train timetables, flight bookings
- Business - orders, stock control, payroll
- Retail - online ordering, logistics systems that control delivery of goods
- Entertainment - DVDs, Blu Ray, MP3 players
- Communication - email, chat, social networks, business transactions, mobile phones
- Education - Virtual Learning Environments, exam marking, unlimited sources of information on the web
- Politics and government - campaigns, voting (in some countries), payment of taxes
- Science - number crunching, simulations, visualisations
- Computer systems are involved in most human activities
- Reliability
- As we have become more dependent on computer systems, we need to be able to trust their reliabilty
- Computer systems are so reliable that we don't give them much thought, but they can sometimes let us down
- Unreliable computer systems can cause very serious problems
- Aeroplanes rely on computer systems, so obviously any problems with these could be lethal
- It is vital that the human operators understand what the computer systems are meant to do
- They can result in the loss or theft of data
- This type of problem is often related to poor procedures or non-compliance with procedures rather than computer system faults
- Aeroplanes rely on computer systems, so obviously any problems with these could be lethal
- Standards
- Standards refer to conventions and rules
- They are normally defined by a responsible organisation
- In computing, standards exist for programming languages, operating systems, data formats, communications protocols and electrical interfaces
- There are various categories of standards
- Proprietary standards
- These are standards owned by an organisation
- They ensure compatibility between the company's products
- They can be used to exclude others from competing with rival products
- For example, Apple computers lock users into using Apple software
- Open standards
- These are publicly available standards that are often agreed by a group of collaborators and are not for profit
- Examples include HTTP, HTML, WAP, TCP/IP, XML and SQL
- Industry standards
- These are set by industry-wide organisations
- Many of these relate to hardware and allow easy interconnection between devices, e.g. USB
- De facto
- These have developed from common usage
- Includes standards such as postscript, the QWERTY keyboard and the Microsoft Word file standard
- These standards lack formal approval and are not recognised by any official standards organisations
- De jure
- This means 'by law'
- They are de facto standards that have become so universally accepted that they have to be adhered to in order for devices and software to be able to communicate
- Examples include wireless 801.11, TCP/IP, ASCII and Unicode
- Proprietary standards
- Standards are important because they:
- Enable equipment from different manufacturers to work together
- Make learning new systems easier
- Minimise waste
- Help to ensure fair play and access to markets
- Bring costs down by opening markets to competition
- Standards refer to conventions and rules
- Ethical, environmental and legal considerations
- Ethical considerations are about what is morally right and wrong
- It comes down to what people or society believe is right or wrong
- These things are not illegal in themselves, but many people have very strong beliefs about whether they are right or wrong
- Environmental considerations are about what is good or bad for the environment
- The components that are used to make hardware devices usually contain plastics which are derived from oil, and metals which are very harmful to the environment
- To encourage recycling, there is an EU directive called WEEE - Waste Electrical and Electronic Equipment
- It places an obligation on an organisation such as schools and hospitals to dispose of old equipment by recycling
- Therefore many companies now use recycling specialists to take away the old equipment and extract as much valuable material from it as possible, with the remainder going into landfill
- Another option is to be in partnership with refurbishment specialists
- They refurbish old computers that still work, then sell them on or donate them to worthy causes
- This has two benefits:
- People who can't afford the latest computers can now use older ones
- Computers stay useful for longer, avoiding landfill or recycling for a while longer
- This has two benefits:
- They refurbish old computers that still work, then sell them on or donate them to worthy causes
- It places an obligation on an organisation such as schools and hospitals to dispose of old equipment by recycling
- To encourage recycling, there is an EU directive called WEEE - Waste Electrical and Electronic Equipment
- Computer systems use up a lot of electricity to run and keep cool
- So manufacturers now design equipment that uses as little energy as possible
- Sleep mode effectively shuts down the computer if it hasn't been used for a while
- Real, physical servers are now so powerful that they spend much of their time doing nothing, because they get the jobs requested of them done in nanoseconds
- This low load is very inefficient - it wastes energy and money
- A virtual server is an 'image' of a complete server that runs as a software program on the physical server
- Many virtual servers can now run on one physical machine, so the loading is much higher
- This means it's more energy efficient
- Many virtual servers can now run on one physical machine, so the loading is much higher
- A virtual server is an 'image' of a complete server that runs as a software program on the physical server
- This low load is very inefficient - it wastes energy and money
- So manufacturers now design equipment that uses as little energy as possible
- The components that are used to make hardware devices usually contain plastics which are derived from oil, and metals which are very harmful to the environment
- Legal considerations are about what is legal or illegal according to the law of the country
- The Computer Misuse Act makes it illegal to gain unauthorised access to computer systems (hacking)
- It also makes it illegal to deliberately damage another person's computer system, for example by introducing a virus in it
- The Data Protection Act gives clear guidelines on how organisations should obtain and process people's personal data
- It demands that those who keep personal data on computer systems should take care of it and protect it from unauthorised people
- The Computer Misuse Act makes it illegal to gain unauthorised access to computer systems (hacking)
- Ethical considerations are about what is morally right and wrong
- Systems
Comments
No comments have yet been made