GCSE A* REVISION NOTES


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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:

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

Proprietary standards

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:

Industry Standards

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.

Open Standards

Standards that are publically available. E.g. TCP/IP (Transmission control protocol/internet protocol)

Examples

Hardware:

Wi-fi: 802.11 b/g/n; Bluetooth, USB, SCSI (obsolete), HDMI (not just computers), E-IDE.

Software:

TCP/IP, HTML, SQL, JASON, ASCII, Unicode.

Explain the importance of ethical, Environmental and legal considerations when creating computer systems.

Environmental

Ethical

Legal

Data Protection Act 1998

Governs how people and organisation have to look after the data they hold about us

The Copyright, Designs and Patents Act 1998

Protects work from being copied without permission

The Computer Misuse Act 1998

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