BCS Glossary of Computing - 14th edition

BCS Glossary of Computing - 14th edition

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The BCS Glossary is the most authoritative and comprehensive work of its kind on the market today. This unrivalled study aid and reference tool has newly updated entries and is divided into themed sections making it more than just a list of definitions. Written in a style that is easily accessible to anybody with an interest in computing, it is specifically designed to support those taking computer courses or courses where computers are used, including GCSE, A-Level, ECDL and 14-19 Diplomas in Functional Skills in schools and further education colleges.

"The text is authoritative yet clear, concise and easily understood. The Glossary is easy to use either by browsing the themed sections or using the comprehensive index.

This resource is used by examination boards as a basis for their definitions and remains the essential reference and support for those teaching or taking computer and ICT courses in schools, FE and universities from GCSE level onwards and cannot be recommended highly enough."

Ian Carey FCIEA, WJEC Subject Officer for Computing/ICT --

"...this is a compact and neat dictionary of terms compiled in a single source. [...] a handy book to have on the shelf."

Dr Siraj A. Shaikh FBCS CITP CSci, Senior Lecturer, Coventry University

Product Details

ISBN-13: 9781780173269
Publisher: BCS Learning & Development Limited
Publication date: 01/09/2016
Edition description: 14th Revised ed.
Pages: 510
Product dimensions: 6.75(w) x 9.62(h) x 1.00(d)
Age Range: 12 - 18 Years

About the Author

Compiled by members of the BCS Academy Glossary Working Party, many of whom are teachers. In creating the glossary, they have drawn heavily upon their many years of experience in the education sector, as well as their detailed knowledge of computing.

Read an Excerpt



When you approach computing for the first time you meet a range of terms that people involved in the industry take for granted. These terms are often vague generalisations and may mean different things to different people. They are also applied to a wide range of situations within computing and their precise meaning may vary between contexts.

Most jargon you meet when using a computer is related to the task you are doing. The software used to perform the task is called an application. Examples of applications include word processing, computer art and using a database program. However, there is some jargon that relates to running the computer itself, that is, how you control or operate a computer.

This section provides general definitions of some of the more common computing terms that are either used in a general context or apply across many areas of computing.


Information processing

is the organisation, manipulation and distribution of information. As these activities are central to almost every use of computers, the term is in common use to mean almost the same as 'computing'. See also data and information page 255.

Information technology (IT)

including: ICT (information and communications technology)

is the application of technology to information processing. The current interest centres on computing, telecommunications and digital electronics.

In the UK schools sector, the preferred term is ICT (information and communications technology).


is a general term describing the communication of information over a distance. The method of communication is normally via a cable, either wire or fibre optic (see page 343) or electromagnetic radiation. See also wireless communication, page 342. Computer data uses the same network as telephone systems.


is a machine that processes data. It takes data, in digital form, which is processed automatically before being output in some way. It is programmable so that the rules used to process the data can be changed. It is an automatic, programmable, digital data processor. These ideas are expanded in the introduction to Section E1, page 287. The definition excludes the analog computer (page 288).

Computer system

including: configuration

is the complete collection of components (hardware, software, peripherals, power supplies, communications links) making up a single computer installation. The particular choice of components is known as the configuration – different systems may or may not have the same configuration.


is the use of a computer to manipulate data or control a process. It is also an umbrella term used in higher education to cover the multitude of subjects relating to computers that can be studied.

Embedded system

is the use of a computer system built into a machine of some sort, usually to provide a means of control. The computer system is generally small, often a single microprocessor with very limited functions. The user does not realise that instructions are being carried out by a computer but simply that there are controls to operate the machine. Examples are electronic washing machines, burglar alarms and car engine management systems.


is the presentation of information by a computer system using graphics, animation, sound and text.

Facilities management

also known as: managed services

is the contracting of an organisation's day-to-day operations to an outside company. The facilities management company employs the staff and runs the operation. Where it is computer operations to be managed, the equipment will usually be sited in the organisation's own premises, although it may be owned or leased by the facilities management company. The contract for this kind of service will specify what the computer system must provide for the price. This is distinct from outsourcing (see page 5), where a well-defined task will be contracted out.


is the purchase of services from outside contractors rather than employing staff to do the tasks. This use of contractors for a well-defined task is distinct from facilities management (see page 4) where day-to-day operations are involved. Traditionally large computer organisations have employed many staff such as systems analysts and developers (see Section B9 Computer personnel). It may be more economic to contract another organisation to provide these services and not have the expense and complication of direct employment of staff. With the use of networking, it is possible to outsource anywhere in the world.

Some of these tasks may be provided by a computer bureau (see below).

Computer bureau

including: data processor

is an organisation that offers a range of computing services for hire (for example, data preparation, payroll processing). Bureaux usually offer two types of service:

• They provide computing facilities for organisations that do not have any of their own.

• They also offer specialist services covering vital common operations (for example, payroll) to organisations that do not have the appropriate piece of applications software.

Compare this with facilities management and outsourcing.

Data processor is the name used in the Data Protection Act (1998) (see page 157), for a computer bureau.



is the physical part of a computer system – the processor(s), input and output devices, and storage. This is in contrast to the software (see page 6), which includes application packages, and the data in the storage.

Storage media

also known as: media

is the collective name for the different types of storage materials (such as compact disc, solid state, memory card, hard disk and even paper) used to hold data or programs. They are used either within the computer system or connected to it. See peripherals (see page 6) and Section E3.


also known as: device

including: input device, output device, input/output device (I/O device), storage device

is a piece of equipment (or hardware) that can be connected to the central processing unit. It is used to provide input, output and backing storage for the computer system. No particular peripheral is required by a computer but every computer must have some method of input and output (for example, a washing machine may simply have push buttons for input and actuators, page 118, for output). They are often referred to as follows:

Input device is a peripheral unit that can accept data, presented in the appropriate machine-readable form, decode it and transmit it as electrical pulses to the central processing unit.

Output device is a peripheral unit that translates signals from the computer into a human-readable form or into a form suitable for reprocessing by the computer at a later stage.

Input/output device (I/O device) is a peripheral unit that can be used both as an input device and as an output device. In some instances, 'input/output device' may be two separate devices housed in the same cabinet.

Storage device is a peripheral unit that allows the user to store data in an electronic form for a longer period of time and when the computer is switched off. The data can be read only by the computer and is not in human-readable form.


including: applications program, application, applications package, generic software, productivity tool

consists of programs, routines and procedures (together with their associated documentation) that can be run on a computer system.

An applications program, frequently abbreviated to application, is software designed to carry out a task (such as keeping accounts, editing text) that would need to be carried out even if computers did not exist.

An applications package is a complete set of applications programs together with the associated documentation (see user documentation, page 425). Where the application is appropriate to many areas, it is usual to describe it as generic software or as a productivity tool. For example, word processing (see page 367) can be used in personal correspondence, the production of business 'form letters', academic research, compilation of glossaries, writing books etc.

See also Section B12 Systems software, program on page 212 and Section C4.

Integrated package

also known as: integrated program

is a single piece of software that provides a user with basic information processing functions. It usually includes word processing, spreadsheets and small databases and may include additional facilities such as charts, a diary and communications. It is designed so that data can be simply moved between the various parts enabling complex tasks to be performed easily.


is a program that helps a user to learn about a new application. The tutorial will include a simple explanation of how to use the new system, diagrams and possibly examples the user can try while the tutorial program monitors the user's progress.



Other related terms may be found in Section A1 General computing terms, and for fuller definitions see Section B12 Systems software.

There are important similarities between the way we use motor vehicles and the way we use computers. In both cases, the majority of users are completely unconcerned about the internal workings of the machine, but are nonetheless capable of becoming skilled in its use. Anyone using this Glossary is likely to be seeking an understanding of what goes on 'under the bonnet', but in this section we look at the terms and definitions that are to do with the general use of computers. The parallel with motorcars continues to be instructive: while most drivers are unaware of the technicalities of the car, they must be acquainted with some features that are not just to do with steering it in the direction they want to go – the need for petrol and oil, and the ways in which a flat battery may be avoided. The explanations in this section are the equivalent for the computer.

Computer tasks can be divided into two broad categories. There are those that have only been made necessary by the existence of the computer – the handling of printers, the storage of data on disks, and so forth. These tasks are performed by systems software and we would not need to undertake these tasks if computers did not exist. However, there is a much more important category of task. These are the things that we would want to do even if computers did not exist, and are generally known as applications, carried out by applications software. It is in this second category that we find word processing, where the computer enhances our ability to create, edit and lay out text. Letters were written and books published long before there were computers. Similarly with spreadsheets, where accountants tallied columns of figures and derived calculations from numeric data even before the mechanical calculator.

In operating a computer, users may find themselves performing the same types of actions in different applications, or even when interacting with systems software. These common operations are collected in this section. The subsection 'The size of things' may seem to be technical, but the terms bit, byte and word, described within it are often used to describe the size or capacity of a computer.

The power of the computer is so great that it is tempting to believe that it has created new applications – things we were unable to do before the computer. However, while the computer may have made some tasks practicable and feasible, in general a little reflection will reveal the possibility (if not the widespread practice) of most applications before the advent of the computer. It is worth remembering that photographers were retouching pictures before digital manipulation of images became commonplace, that librarians maintained card indexes before databases, that letters were sent before emails, and that musicians were creating electronic music before computers.

Perhaps the most likely candidate for a truly new application is in the use of the internet, and especially the World Wide Web. It is hard to see which human activity in pre-computer days parallels the creation of the personal statements of interests and activities that appear on web pages, much less the growth of ecommerce. That is, until we remember letters, newsletters, magazines and mail order catalogues!


Operating system (OS)

is the name given to the collection of systems software that manages the computer. It is usually supplied with the computer. The most common operating systems today are Microsoft® Windows® and LINUX® (for the PC), Apple® Mac® OS (for the Macintosh®) and UNIX® (for larger computers). The operating system gives the computer its 'look and feel', and generates great passion between advocates of alternative systems. See also Section B12 Systems software.


is a piece of system software supplied with a peripheral (such as a printer, a mouse, a display screen or a keyboard). It bridges the gap between the operating system and the peripheral, and converts commands from one into instructions that the other can obey. In this way, applications software such as a word processor can, for example, issue a 'print' instruction in a standard way to the operating system, without needing to know the details of the particular printer being used. The casual user may meet drivers when he or she installs or upgrades a peripheral.


including: graphics filter

is a piece of software used in conjunction with an application, which allows data stored in one format to be accessed by an application that uses another format. For example a word-processing package, such as Microsoft® Word, will provide filters for documents created in its major competitors, such as WordPerfect®. In this way, users will not be dissuaded from buying Microsoft® Word because all their previous work was created in WordPerfect®. Even between software created by the same manufacturer, a filter may be necessary, for example to import a spreadsheet into a database package. It may not always be possible to convert every feature supported by one format into another format. The user is unlikely to be aware of a filter unless he or she encounters an error message reporting the failure or absence of an appropriate one.


Excerpted from "BCS Glossary of Computing"
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Copyright © 2016 BCS Learning and Development Limited.
Excerpted by permission of BCS The Chartered Institute for IT.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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Table of Contents

How to use this Glossary
Part A: How computer systems are used
Part B: What computer systems are made of
Part C: How computer systems are developed
Part D: How computers work
Part E: Reference

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