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A |
| analog |
| Signal which does not vary in discrete steps, but continuously from one level to another. For storage, processing and communicating with computers, analog signals (such as the output of a microphone) are converted into digital form using analog to digital converters (A-to-D or A/D). This is called digitization, as the information is then stored in binary code. See also digital. (synonym)
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| apple |
| A computer company best known for making Macs and iPods
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| ASCII |
| acronym for 'American Standard Code for Information Interchange'. Internationally adopted standard of numerical equivalents for characters representing numbers, letters, punctuation marks, symbols, and control codes. ASCII gives rise to plain text which can be read by most computers and most text-reading software.
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B |
| backbone |
| A backbone is a high-speed communication link used to provide the main links between the smaller sub-networks in a large network. The connections are fibre optic cable.
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| bit |
| contraction of 'binary digit'. The smallest unit of computer information, equal to either of the digits 0 or 1, called binary because it has only two values, on or off.
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| Boolean operator |
Also known as 'logical operator', word or symbol which defines a logical relationship between two data items. This relationship can be 'AND', 'OR' or 'NOT'. For example, searching a database can be made more efficient by using Boolean operators with the search terms, so that only terms which occur together are retrieved (using AND) and others are excluded (using NOT).
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| broadband |
| informally used to mean 'faster than common networks', and so the actual meaning depends on what is common at the time. Currently broadband is regarded as starting at 34 Mbit/sec (Mbps) – under this classification, all commonly occurring local area networks (such as Ethernet) are narrowband.
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| Burn |
| The process of recording data onto a CD or DVD.
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| bus network |
| A type of local area network, a bus network has each of the devices connected directly to a main communications line, called a bus, along which signals are sent. The bus will frequently be a twin cable of some kind, for example, coaxial cable.
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| byte |
| unit of information equal to eight bits. Usually, each byte stores one character.
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C |
| central processing unit (CPU) |
| The central processing unit (CPU) is the main part of the computer, consisting of the registers, arithmetic logic unit and control unit. Usually the central processing unit includes the main memory. It is sometimes called the central processor or processor. Many computers have more than one processor. A special form of central processing unit is the microprocessor which is used in microcomputers and small computerised devices, for example the control circuits of washing machines.
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| client |
| In a network, a client is a computer which asks for services from a server, for example, a file server or print server.
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| clock speed |
| The clock speed (or clock rate) is the frequency at which the clock generates pulses. The higher the clock rate, the faster the computer may work. The speed is expressed in megahertz (MHz) (millions of cycles per second).
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| coaxial cable |
| Coaxial cable is the same kind of cable that is used for connecting a television aerial to a television set. It has two conductors. One is a wire down the centre of the cable, which may be a single strand, insulated from the second, which is made up of many strands braided around the insulation for the inner wire. |
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| control unit |
| The part of the central processing unit which manages the execution of instructions. The control unit fetches each instruction in sequence, and decodes it, before executing it by sending control signals to other parts of the computer.
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E |
| electronic whiteboard |
An electronic whiteboard (also known as an interactive whiteboard) connects to a computer and not only displays the contents of the computer monitor, but also has the facility for users to edit and save the content on the whiteboard, using either a special pen or by touching the screen with a finger or hand.
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F |
| fibre optic cable |
| A very fine glass strand that allows rapid transmission of data, using modulated light beams. It is usual to put many strands together in a single cable, each one capable of carrying one or more data signals. Fibre optic cable provides interference-free, secure data transmission and, unlike metal wires, is not subject to corrosion. Also known as optical fibre. |
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| fifth-generation compute |
| A vision of a totally different way of designing and using computer systems. It involves both new computer architectures and types of software, and some of this vision has been achieved. It focuses on virtual reality, expert systems and natural language interfaces that can interact with people.
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| first-generation computer |
| The first type of computers. They used valves, mercury delay lines, electrostatic memories and had very limited storage.
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| fourth-generation computer |
| The type of computer used today. Fourth-generation computers are similar to third-generation computers, except a much greater use of large-scale integration of components on silicon chips, which resulted in increasing similarity of design. A large fall in the cost of internal memory, and higher speed and capacity of external storage, led to new applications and new methods of programming. Also, people realised that standardisation of software, particularly operating systems, was necessary. |
