Fundamentals of Computer Systems
Define a computer system
A combination of hardware and software components that allow input, processing and output of data
Describe the importance of computer systems in the modern world
Computer systems are used in every aspect of our lives from entertainment to health care. If they go wrong it can cause massive problems.
Explain the need for reliability in computer systems
Reliability - The probability that a computer will produce the correct output in a given time frame. Can be measured using uptime as a percentage of hours the system has been available. Expected reliability of individual parts of the system can be measured in MTBF (Mean Time Before Failure).
Safety/Life Critical systems – A system were failure may result in death, loss or severe damage to equipment that may led to death or injury
To improve reliability:
- the system must have a clear design that satisfies user requirements
- the system must be designed with safety and possible failure in mind
- the design must make testing easy and include test plans
- the design must be developed according to defined standards
- testing should be carried out throughout development
- maintenance should be carried out after the system goes live
- systems can have failsafe mechanisms built in
- the system must be designed and created according to defined standards.
In safety critical systems have redundancy plans with multiple backup computers running in parallel with the main system. In the case of a failure the switch to backup can happen without any interruption.
Explain the need for adherence to suitable professional standards in the development, use and maintenance of computer systems
Having hardware that conforms to standards means that a device bought for one computer will work on any other
ISO (International Organisation for Standardisation) – The world’s largest standards development organisation
These are standards owned by a company. For example, software running on windows that must work in a certain way. The advantages of this are:
- look and feel familiar to users and will speed up learning new systems
- work in a predictable way which will improve reliability
- be maintained by one company
Standards agreed across the industry to allow easy interconnection between devices. E.g. USB
De Facto Standards
Standards that develop through common usage. For example, Microsoft word .doc has become the de facto standard for word processed documents.
Standards that are publically available. E.g. TCP/IP (Transmission control protocol/internet protocol)
Wi-fi: 802.11 b/g/n; Bluetooth, USB, SCSI (obsolete), HDMI (not just computers), E-IDE.
TCP/IP, HTML, SQL, JASON, ASCII, Unicode.
Explain the importance of ethical, Environmental and legal considerations when creating computer systems.
- Electrical items are marked as not for waste
- Many computers contain toxic and carcinogenic components and so in the USA old computers are classified as hazardous waste
- Many electronical items also contain useful metals that can be reused and recycled
- However, the cost of recycling drives companies to export their waste abroad or dump it
- Computer systems use more energy than the aviation industry
- This is a concern as supplies of energy are finite and expensive
- So they should be switched off when not in use
- Some electrical waste is donated to developing countries
- Codes of values are needed as computer professionals have access to a lot of sensitive information that could be misused
- BCS (British Computer Society) provides a code of conduct that its members must adhere to
Data Protection Act 1998
Governs how people and organisation have to look after the data they hold about us
- If a company wishes to hold information about individuals they must register with the information commissioner’s office (ICO) and adhere to the prinicples:
- Data must be processed fairly
- It can only be used for its intended purpose
- They should only hold data they need
- Data must accurate and up to date
- Data must not be held longer than it is needed for
- Data will be used in accordance with your rights
- Data will be kept safe
- Data will not be transferred to any country where they don’t have similar laws
The Copyright, Designs and Patents Act 1998
Protects work from being copied without permission
The Computer Misuse Act 1998
- Illegal to attempt to access data that you are not authorised to
- Illegal to attempt to access data with the intention of committing a crime
- Illegal to attempt to access data with the intention to change the data or impair the running of the computer; can have up to 10 years in jail