BCS GLOSSARY OF COMPUTING AND ICT

BCS, THE CHARTERED INSTITUTE FOR IT

Our mission as BCS, The Chartered Institute for IT, is to enable the information society. We promote wider social and economic progress through the advancement of information technology science and practice. We bring together industry, academics, practitioners and government to share knowledge, promote new thinking, inform the design of new curricula, shape public policy and inform the public.

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Further InformationBCS, The Chartered Institute for IT,First Floor, Block D,North Star House, North Star Avenue,Swindon, SN2 1FA, United Kingdom.T +44 (0) 1793 417 424F +44 (0) 1793 417 444www.bcs.org/contact

BCS GLOSSARY OF COMPUTING AND ICT13th edition

Edited by the BCS Academy Glossary Working Party

Members of the Working PartyArnold BurdettDan BowenDiana ButlerAline CummingDavid FullerFrank HurvidAdrian JacksonJohn JaworskiPercy MettThomas NgPenny PattersonMarianne ScheerHazel ShawAlfred VellaJohn Woollard

Former members of the Working Party (whose work is included in this edition)Diana Burkhardt, Brian Jackson, Alan Hunter, Laurie Keller, Graham Rogers, Tim Reeve, John Southall

1st edition, BCS © 1977 BCS, reprinted 1978, 19782nd edition, BCS © 1979 BCS, reprinted 19803rd edition, BCS © 1982 BCS4th edition, CUP & BISL © 1984 BISL, reprinted 1985, 19865th edition, CUP & BISL © BISL6th edition, CUP & BISL © BISL7th edition, Pitmans/Longmans © 1991 BISL, reprinted 1993, 19948th edition, Longmans © 1995 BISL, reprinted 1996, 19979th edition, Addison Wesley Longmans © 1998 BISL10th edition, Pearson Education © 2002 BCS11th edition, Pearson Education © 2005 BCS, reprinted 200512th edition, BCS © 2008 BCS13th edition © 2013 BCS Learning and Development Limited

All rights reserved. Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted by the Copyright Designs and Patents Act 1988, no part of this publication may be reproduced, stored or transmitted in any form or by any means, except with the prior permission in writing of the publisher, or in the case of reprographic reproduction, in accordance with the terms of the licences issued by the Copyright Licensing Agency. Enquiries for permission to reproduce material outside those terms should be directed to the publisher.

All trade marks, registered names etc. acknowledged in this publication are the property of their respective owners. BCS and the BCS logo are the registered trade marks of the British Computer Society charity number 292786 (BCS).

Published by BCS Learning and Development Limited, a wholly owned subsidiary of BCS, The Chartered Institute for IT, First Floor, Block D, North Star House, North Star Avenue, Swindon, SN2 1FA, UK.www.bcs.org

ISBN: 978-1-78017-150-0PDF ISBN: 978-1-78017-151-7ePUB ISBN: 978-1-78017-152-4Kindle ISBN: 978-1-78017-153-1

British Cataloguing in Publication Data.A CIP catalogue record for this book is available at the British Library.

Disclaimer:The views expressed in this book are of the author(s) and do not necessarily reflect the views of BCS or BCS Learning and Development Ltd except where explicitly stated as such. Although every care has been taken by the authors and BCS Learning and Development Ltd in the preparation of the publication, no warranty is given by the authors or BCS Learning and Development Ltd as publisher as to the accuracy or completeness of the information contained within it and neither the authors nor BCS Learning and Development Ltd shall be responsible or liable for any loss or damage whatsoever arising by virtue of such information or any instructions or advice contained within this publication or by any of the aforementioned.

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We dedicate this book to John Southall.

John was a member of the BCS staff and Registrar. He was instrumental in forming the Working Party of BCS Schools Committee members in the 1970s that started the small Glossary, which evolved over the years into the current edition.

John’s wit, wide knowledge of computer terminology and of BCS, and his attention to detail, made him a strong support for those who follow on. He was

working on this thirteenth edition when he died.

CONTENTS

Figures and tables xi

INTRODUCTION XV Acknowledgements xvi Disclaimer xvii

HOW TO USE THIS GLOSSARY XVIII

PART A: HOW COMPUTER SYSTEMS ARE USED 1

A1 GENERAL COMPUTING TERMS 3 Information processing 3 Parts of the computer system 5

A2 USING YOUR COMPUTER 7 System software 8 Organising data 9 The size of things 12 Operation 13

A3 WORD PROCESSING AND TEXT MANIPULATION 20 Software 20 Processes 23 Elements of print 25 Layout 28 Styles 32

A4 GRAPHICS, DESIGN AND DIGITAL IMAGING 35 Image data formats 35 Graphic design applications 38 Digital still imaging 43 Digital video 44

A5 SOUND 49 Characteristics of sound 50 Sound processing 53 Devices 58

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CONTENTS

A6 USER INTERFACE AND DOCUMENTATION 62 Graphical interfaces 63 Other interface styles 69 Documentation 71

A7 COMMERCIAL DATA PROCESSING (DP) 74

A8 SPREADSHEETS 83

A9 DATA HANDLING AND INFORMATION RETRIEVAL 90

A10 MODELLING AND SIMULATION 105

A11 INTERNET 109 Accessing the internet 110 Organising the internet 113 World Wide Web 115 Electronic mail 120 Other internet applications 123 Internet problems 128

A12 NETWORKING 130

A13 CONTROL AND MONITORING 144 Control 145 Virtual reality 147

A14 ARTIFICIAL OR MACHINE INTELLIGENCE 149

A15 COMPUTER PERSONNEL 155

A16 COMPUTER SECURITY, ABUSE AND RELATED LAW 160 Data security 161 Viruses and malicious code 171 Copyright 172

A17 SPECIALISED COMPUTER APPLICATIONS 175

PART B: WHAT COMPUTER SYSTEMS ARE MADE OF 181

B1 TYPES OF COMPUTER 183

B2 INPUT 188 Manual input 189 Automated input 191

B3 MEMORY 193 General concepts 195 Disk 196 Miscellaneous forms of memory 200 General 202

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CONTENTS

B4 OUTPUT 204 Colour 206 Quality 208 Display 210 Printing 212

B5 COMMUNICATIONS COMPONENTS 219

PART C: HOW COMPUTER SYSTEMS ARE DEVELOPED 225

C1 SYSTEMS DESIGN AND LIFE CYCLE 227 Concepts 228 Stages 231 Project management 234 General 238

C2 DESCRIBING SYSTEMS 245

C3 PROGRAMMING CONCEPTS 259 Object-oriented techniques 260 Traditional programming techniques 262

C4 PROGRAMMING (FLOW OF EXECUTION) 272

C5 PROGRAMMING (SUBPROGRAMS) 278

C6 PROGRAM SYNTAX 284

C7 DESCRIBING PROGRAMS 290

C8 TESTING AND RUNNING PROGRAMS 298

C9 PROGRAMMING LANGUAGES 307 Levels of language 309 Types of language 314 Miscellaneous specialised languages 316

C10 DATA REPRESENTATION 323 Concepts 323 Structures 325 Elements 329

C11 NUMERIC DATA REPRESENTATION 332

C12 MANAGING DATA FILES 339 Files 339 Operations 344 General 349

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CONTENTS

PART D: HOW COMPUTERS WORK 353

D1 SYSTEMS SOFTWARE 355 Concepts 356 Development 358 Operations 362

D2 MACHINE ARCHITECTURE 366 The processor 367 Memory 370 General concepts 372 Interfaces 377 Physical components 378

D3 COMMUNICATIONS TECHNOLOGY 383 Transmission 384 Protocols 386 Signals 389

D4 TRUTH TABLES AND LOGIC GATES 394 Binary logic 394 Gates 396

PART E: REFERENCE 403

E1 ACRONYMNS AND ABBREVIATIONS 405

E2 UNITS 423

E3 FILENAMES AND FILENAME EXTENSIONS 426

E4 GEOGRAPHIC DOMAIN IDENTIFIERS 430

E5 ASCII CHARACTER CODES 433

Index 436

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FIGURES AND TABLES

Figure A2.1 Filters 9Figure A2.2 Two examples of customising 14Figure A2.3 Default options 15Figure A2.4 Horizontal scroll bar 18Figure A3.1 A word processor (top) and a destop publishing

package (bottom) 21Figure A3.2 Web editor 22Figure A3.3 Checking a document 24Figure A3.4 Mailmerge 25Figure A3.5 Italic fonts 27Figure A3.6 Tab stops 30Figure A3.7 Use of tabs 30Figure A3.8 Use of tables 31Figure A3.9 Justification of text 31Figure A3.10 Style definition dialogue box 33Figure A4.1 Vector graphics, at two scalings 39Figure A4.2 A graphics tablet and stylus 40Figure A4.3 A typical bitmapped graphic 40Figure A4.4 Examples of photo editing 41Figure A4.5 An example of image enhancement 42Figure A4.6 Typical clip art 43Figure A4.7 Typical semi-professional video-editing system 47Figure A5.1 A waveform (the opening of a Strauss waltz) 50Figure A5.2 Characteristics of a (sound) wave 51Figure A5.3 Harmonics and timbre (1) 52Figure A5.4 Harmonics and timbre (2) 52Figure A5.5 Stereophonic sound 53Figure A5.6 Volume envelope 54Figure A5.7 Two pitch envelopes 54Figure A5.8 Sampling 56Figure A5.9 The effect of sampling rates 56Figure A5.10 A typical computer sound-processing package 60Figure A6.1 Dialogue box 66Figure A6.2 List box 66Figure A6.3 Toolbar 67Figure A6.4 Directory tree 68Figure A6.5 Conversational dialogue screen 69Figure A6.6 Forms dialogue screen 70Figure A7.1 An example of a QR code 79

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FIGURES AND TABLES

Figure A7.2 Clock track on a machine-readable document 79Figure A8.1 A typical spreadsheet 83Figure A8.2 Cell contents 84Figure A8.3 ‘What if?’ 85Figure A8.4 Chart options 85Figure A8.5 A cell block 86Figure A8.6 Replication 87Figure A8.7 Spreadsheet for a single shop 89Figure A8.8 Two views of data from several shops 89Figure A9.1 How a database management system works 92Figure A9.2 A flat file or two-dimensional table 93Figure A9.3 Hierarchical database 93Figure A9.4 Sample metadata listing for a digital camera image 95Figure A9.5 An example of data in normal form 96Figure A9.6 An example of data modelling 99Figure A9.7 A typical report 101Figure A11.1 Anatomy of a website 116Figure A11.2 Hyperlink 118Figure A11.3 Search engine 119Figure A11.4 The anatomy of an email 121Figure A12.1 A bus network with spurs 132Figure A12.2 A bus network 133Figure A12.3 A ring network with spurs 133Figure A12.4 A ring network 134Figure A12.5 A star network 135Figure A12.6 A backbone with three subnetworks 135Figure A12.7 An example of a modern computer network 142Figure A14.1 An expert system structure 153Figure A16.1 Firewalls and proxy servers 166Figure A16.2 How a public key cryptosystem works 170Figure B3.1 Tracks on a disk and a cylinder 197Figure B3.2 Cache memory 202Figure B4.1 A character formed by a pattern of dots 205Figure B4.2 Dithering 207Figure B4.3 Data flow in a colour management system 208Figure B5.1 Multiplexors connecting remote workstations to a computer 220Figure B5.2 Section of coaxial cable 222Figure C1.1 Relationship between the three cycles 230Figure C1.2 An example Gantt chart 236Figure C1.3 An example of Critical Path Analysis 237Figure C2.1 An example of a block diagram (courtesy Acorn Computers) 246Figure C2.2 Information flow diagram symbols 247Figure C2.3 An example of an information flow diagram 247Figure C2.4 Data flow symbols 248Figure C2.5 Level 1 data flow diagram of the payroll process 248Figure C2.6 Entity-relationship diagram used in designing a database 249Figure C2.7 System flowchart symbols 250Figure C2.8 An example of system flowchart using alternative symbols 251Figure C2.9 A structure diagram for the payroll process 252Figure C2.10 Expansion of process 3.20 in Figure C2.9 253

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FIGURES AND TABLES

Figure C2.11 Flowchart symbols 253Figure C2.12 An example of a flowchart 254Figure C2.13 An example use case diagram 255Figure C2.14 An example sequence diagram 256Figure C2.15 An example activity diagram 257Figure C2.16 An example class diagram 258Figure C2.17 An example statechart diagram 258Figure C3.1 An example of an algorithm in pseudo-code 264Figure C3.2 An example of an assignment statement 264Figure C3.3 Logical operation on a bit pattern 267Figure C3.4 Examples of display and print format statements 269Figure C4.1 Examples of count-controlled loops 273Figure C4.2 Examples of condition-controlled loops 274Figure C4.3 Examples of selection statements 275Figure C4.4 Examples of multiple selection 277Figure C5.1 An example of a function 279Figure C5.2 Examples of a recursive subprogram 281Figure C5.3 Examples of parameters 282Figure C5.4 Examples of parameter passing to a function 283Figure C6.1 Examples of block structure 285Figure C6.2 An example of the use of a dummy variable 287Figure C6.3 An example of ‘+’ operator 287Figure C6.4 Examples of unary and binary operators 288Figure C6.5 Examples of relational operators in pseudo-code 288Figure C7.1 A decision table 292Figure C7.2 Connector or continuation symbol 292Figure C7.3 Input/output symbol 293Figure C7.4 Alternative forms of decision box 293Figure C7.5 Process symbol or box 294Figure C7.6 Start/stop symbol or box 294Figure C7.7 Subroutine symbol or box 294Figure C7.8 An example of program module flowchart (in traditional form) 295Figure C7.9 An example of program module flowchart (continuation) 296Figure C7.10 Program module in pseudo-code 296Figure C7.11 An example of program module flowchart

(using very simple boxes) 297Figure C8.1 Examples of trace tables 302Figure C8.2 Program process states 304Figure C9.1 Example of the use of a logical language 316Figure C9.2 Example of Backus–Naur form 318Figure C10.1 A typical tree structure 325Figure C10.2 A one-dimensional array 326Figure C10.3 A two-dimensional array 327Figure C10.4 Declaring array dimensions 327Figure C10.5 Fields and records in a data file 330Figure C10.6 Key fields in a data file 330Figure C11.1 Number ranges for different number forms 333Figure C11.2 Fixed-point and floating-point representation 335Figure C11.3 Denary to BCD conversion 336Figure C11.4 Binary to octal conversion 337

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FIGURES AND TABLES

Figure C11.5 Binary to hexadecimal conversion 337Figure C12.1 An example of two data sets being merged using

‘Name’ as the key field 346Figure C12.2 An example of two data sets being merged using

‘ID’ as the key field 346Figure C12.3 Two examples of a data set being sorted, one using ‘ID’

and the other ‘Surname’ as the key fields respectively 347Figure C12.4 Comparing the two methods of searching for the key ‘Singh’ 348Figure C12.5 A simple example of data compression 350Figure D2.1 Arithmetic shifts 375Figure D2.2 Logical shifts 375Figure D2.3 Cyclic shifts 376Figure D2.4 DIP switches 382Figure D3.1 Unmodulated carrier wave 389Figure D3.2 Modulation by switching the wave off 390Figure D3.3 Modulation by changing the amplitude 390Figure D3.4 Modulation by changing the frequency 390Figure D3.5 Phase modulation 391Figure D4.1 Karnaugh map 395Figure D4.2 Venn diagrams 396Figure D4.3 NOT gate 397Figure D4.4 OR gate 398Figure D4.5 AND gate 398Figure D4.6 NOR gate 399Figure D4.7 NAND gate 399Figure D4.8 XOR or NEQ gate 400Figure D4.9 XNOR or EQ gate 401

Table A2.1 Common filename extensions 10Table A4.1 Image compression formats 37Table A5.1 Audio storage and compression schemes 57Table A5.2 The effect of sampling and format on file sizes 58Table B3.1 Optical storage 199Table B4.1 Printers 214Table C1.1 System life cycle 229Table C1.2 Software development cycle 230Table C3.1 Examples of different algebraic notations 263Table C3.2 Examples of formatting numeric and date data 270Table C9.1 Early programming languages 310Table C9.2 Programming languages 312Table C9.3 A small selection of common HTML tags 320Table C11.1 Number of patterns provided by different numbers of bits 332Table C12.1 Suitability of file access methods 341Table D2.1 Common interfaces 379Table D3.1 Seven-layer network organisation model (ISO 7) 386Table D3.2 Relationship between OSI and TCP/IP protocols 387

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INTRODUCTION

This Glossary, which contains over 3400 terms, provides not only a comprehensive definition of each term, but also sufficient additional material to enable the reader to understand the importance of the term, how to use it appropriately and its relation to other terms used in the same area of computing. To this end terms are gathered into five parts, describing how computer systems are used, what they are made of, how they are developed and how computers work. The fifth part consists of reference material.

Who is the Glossary aimed at?One of the principal aims of the Glossary is meeting the needs of pupils who follow courses leading to examinations in schools and colleges at a variety of levels. The authors attempt to ensure that the Glossary reflects develop-ments in the National Curriculum for England and Wales, GCSE, AS-Level and A-level specifications, Functional Skills in ICT, the Scottish Curriculum and the Northern Ireland system. At the same time it is intended to improve understanding and literacy in the subject matter.

It is a definitive reference source, mentioned in examination syllabuses. The content has found wide acceptance in universities and colleges for foundation courses as well as induction sessions and training courses. It is used in support of the European Computer Driving Licence (ECDL), within government depart-ments and industry generally. The Glossary has also proved popular with home-based computer users.

How are the individual terms decided on?BCS Glossary Working Party members continuously monitor relevant new and redundant terms and changes in usage. These are amended when it is felt appropriate by the members, as they become sufficiently established and widespread or have fallen out of use.

The Glossary provides definitions that cover the use of terms in the context of both very large computer systems and hand-held equipment. Although large computer systems may be outside the experience of many users, they are likely to encounter consequences of the use of such systems. It should be noted that some terms are included that have a different meaning in a computing environ-ment to that in use in other subjects.

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INTRODUCTION

What are the origins of the Glossary?The Glossary was first published over 30 years ago and has developed from a tiny listing to its current content. In 1974, the British Computer Society was invited by the Regional Examining Boards for the Certificate of Secondary Education to produce a standardised list of terms for use in computer studies courses, examination syllabuses and for their own reference. The Schools Committee of BCS set up a Working Party with a remit to produce a ‘one-off ’ document containing about 100 terms. At the time, there was only one A-level comput-ing examination and a small number of examinations for 16 year olds. Schools involved in computer studies relied on batch processing, preparing and sending their punched cards to university computing centres. A very few had access to an online terminal connecting to the local authority computer. Microcomputers were virtually unknown in schools. At this time almost all sources of computing expertise were inventing their own vocabulary.

Teachers soon requested that the Glossary be made available to pupils. At the end of 1974 work began on the first ‘public’ edition. This edition appeared in 1977, containing approximately 430 terms of which 260 were defined. Given that the target audience was the 14–16-year-old pupil, it was decided that, as far as possible without compromising technical accuracy, simple English should be used in the explanation of the term – an objective still retained wherever possible.

The popularity of the first BCS Glossary resulted in several reprints and the demand for further editions. These latter included new terms that were appear-ing almost daily. This publication was required to keep pace with the rapid development of the technology and with the increasing use of computers in education. It has been the practice of BCS, The Chartered Institute for IT, to update the Glossary approximately every three years.

The Working Party has a changing membership drawing on a wide range of expertise from the computing community.

DevelopmentEarly editions of the Glossary were lists of defined terms and hence resembled a dictionary. Over many editions the Working Party steered the Glossary to its present themed and structured layout.

ACKNOWLEDGEMENTS

The Working Party has appreciated the help it has received from members of Computing At School, and earlier from BCS members and the BCS Schools Committee, for their comments and suggestions about material to include in this edition.

We would like to mention Simon Chalton of Bird & Bird and Les Fraser who contributed significantly to the Computer Security and Data Protection references in Section A16.

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INTRODUCTION

The Working Party also welcomes offers from teachers willing to involve their pupils in a review of this edition and would like to express its thanks to those who have already commented, criticised and made helpful suggestions.

Please send comments by post to: BCS, The Chartered Institute for IT, Publishing, First Floor, Block D, North Star House, North Star Avenue, Swindon, SN2 1FA.www.bcs.org/contact

Alternatively contact any member of the Working Party through BCS.

DISCLAIMER

Neither BCS, The Chartered Institute for IT, nor contributors to the Glossary shall have any responsibility for loss suffered as a result of reliance on the Glossary, and readers should take legal advice on the application of the terms covered particularly in Section A16, which is intended as an aid to understand-ing computer security. The Glossary is not a definitive statement of the meaning of terms.

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HOW TO USE THIS GLOSSARY

The only place you will find a full alphabetical list of all the terms covered in the Glossary is in the index at the back of the book. The Glossary is not a diction-ary and the definitions are not in general arranged alphabetically, even within the sections. Knowing how to use the index is crucial to deriving the maximum value from the Glossary.

For example, looking up ‘virus checking’ in the index leads you to page 171. ‘Virus checking’ is not one of the main definitions on this page, but you will find it under ‘antivirus software’. Your eye should be led to it by the different appear-ance of the term you are searching for: Virus checking.

Antivirus software also known as: vaccine utility including: anti-virus monitor, virus checking, disinfection, quarantine, computer hygiene is used to detect and remove viruses, see page 171.

Antivirus monitors are programs loaded permanently in memory continually moni-toring the system for the tell-tale patterns indicating the presence of any of the thousands of viruses that have been identified. If any change is detected, the file is prevented from being run and a warning message is given. New data read into the computer is also screened for viruses and appropriate action taken.

Virus checking scans the files on a computer system to detect viruses.

Disinfection is the removal of viruses that have been detected.

Quarantine is the isolation of a file suspected of containing a virus. The file can then be investigated and the operation of the virus can be analysed.

Computer hygiene is the term used to describe the prevention and cure of problems caused by viruses.

An alternative way of finding the appropriate entry is to examine the lines immedi-ately after the main entry: ‘also known as’, ‘including’. These provide a list of terms covered in that definition.

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HOW TO USE THIS GLOSSARY

The Glossary is divided into five parts as described in the Introduction. Each part is divided into sections defining terms on a particular topic and large sections are further subdivided. It is hoped that readers will take advantage of this structure to browse within sections; to assist in this, each section has a general introduction (see, for example, page 160 to page 161) providing additional information that puts the terms into context.

Within most definitions, you will find references to other terms (for example, ‘virus’) in the first line of the definition. You may wish to read these in conjunction with the definition you are examining.

There are, of course, other ways of using this glossary. Related terms occur together, and you may find it helpful to read through a complete section or subsection.

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PART A: HOW COMPUTER SYSTEMS ARE USED

A1 General computing terms 3A2 Using your computer 7A3 Word processing and text manipulation 20A4 Graphics, design and digital imaging 35A5 Sound 49A6 User interface and documentation 62A7 Commercial data processing (DP) 74A8 Spreadsheets 83A9 Data handling and information retrieval 90A10 Modelling and simulation 105A11 Internet 109A12 Networking 130A13 Control and monitoring 144A14 Artificial or machine intelligence 149A15 Computer personnel 155A16 Computer security, abuse and related law 160A17 Specialised computer applications 175

This section contains terms that may be met by any computer user working with applications in any of the areas covered. Some sections in Part A are concerned with general issues and others with well-defined areas of computer use. Some sections contain terms that might have been placed in Part B or even in Part C or Part D, but they were kept with other related terms for completeness; this is particularly true of the sections covering the internet, sound and user interfaces, as they became more prominent aspects of computer use. Some terms have references to terms in Part B, Part C or Part D that will provide readers with pointers to other associated terms and concepts.

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A1 GENERAL COMPUTING TERMS

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

Information processingis 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 323.

Information technology (IT)including: ICT (information and communications technology) is the application of technology to information processing. The current interest cen-tres on computing, telecommunications and digital electronics.

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

Telecommunicationsis 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 222) or electromagnetic radiation. See also wireless communication, page 221. Computer data uses the same network as telephone systems.

3

BCS GLOSSARY OF COMPUTING AND ICT

Computeris 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 B1, page 183. The definition excludes the analog computer (page 184).

Computer systemincluding: configurationis 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.

Computingis 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 systemis 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 micro-processor 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.

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

Facilities managementalso known as: managed servicesis 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 facil-ities 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 4), where a well-defined task will be contracted out.

Outsourcingis 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 A15 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.

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GENERAL COMPUTING TERMS

Some of these tasks may be provided by a computer bureau (see page 5).

Computer bureauincluding: data processoris 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 162), for a computer bureau.

PARTS OF THE COMPUTER SYSTEM

Hardwareis 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 mediaalso known as: mediais 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 5) and Section B3, page 193.

Peripheralalso known as: device including: input device, output device, input/output device (I/O device), storage deviceis a piece of equipment (or hardware) that can be connected to the central process-ing 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 145, 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.

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BCS GLOSSARY OF COMPUTING AND ICT

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 elec-tronic 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.

Softwareincluding: applications program, application, applications package, generic software, productivity toolconsists 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 71). 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 20) can be used in personal correspondence, the production of business ‘form letters’, academic research, compilation of glossaries, writing books etc.

See also Section D1 Systems software, program, page 284 and Section C6.

Integrated packagealso known as: integrated programis 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.

Tutorialis 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 whilst the tutorial program monitors the user’s progress.

6

INDEX

1NF (first normal form) 95, 96–972NF (second normal form) 97–98, 1013G 1123GL 3093NF (third normal form) 98–99, 1014G 1124GL 309

A&B signals 53abbreviations 405–422abort 305absolute address 262absolute code 270absolute reference 88acceptance testing 241access rights 167–168access time 382 disk access time 197accounting package 175accumulator 373ACK (acknowledge) signal 392acronyms 405–422action bar 65active device 146active system 144active window 64activity diagram 255–256, 257actual parameter 282actuator 145adaptive maintenance 268add-on software 358additive synthesis 57address 262 absolute address 262 base address 262 email address 122 IP address 114 relative address 262 in spreadsheet 86 store address 195address book 122address bus 372address calculation 370address field 267address modification 370address register 369address-generating algorithm 340, 342addressing direct addressing 370 immediate addressing 370 indexed addressing 370 indirect addressing 370

symbolic addressing 268ADSL (asymmetric digital subscriber line) 111ADSR (attack, decay, sustain, release) 54Advanced Encryption Standard (AES) 169AES (Advanced Encryption Standard) 169aggregator 120agile development 231AI (artificial intelligence) 149–150algebraic notation 262–263algorithm 263 address generating algorithm 340, 342 genetic algorithm 340 hashing algorithm 340 LZW algorithm 349 program algorithm 263, 264 RSA algorithm 170 sorting algorithm 346alpha channel 38alpha testing 240alphanumeric data 331ALU (arithmetic logic unit) 373AM (amplitude modulation) 390American Standard Code for Information Interchange (ASCII) 324, 433–435

amplitude 50, 51amplitude modulation (AM) 390analog computer 184analog signal 222–223analog synthesiser 59analog-to-digital (A-to-D) converter 223analogue sensor 146AND gate 398AND operation 103, 266animation, computer 44annotations 23anonymous FTP 124anti-virus monitor 171anti-virus software 171–172API (application program interface) 240app 124append 344application 6application generation language 309application program interface (API) 240

application server 138applications package 6applications program 6applications programmer 157arc 153archive 77–78archive file 343argument 282arithmetic logic unit (ALU) 373arithmetic operator 288arithmetic register 373arithmetic shift 374–375arithmetic unit 373ARQ (Automatic Repeat Request) 388array (data structure) 326–328array (machine-code programming) 262array bound 328arrow key 65article number 78artificial intelligence (AI) 149–150ASCII (American Standard Code for Information Interchange) 324, 433–435

assembler 358–359assembler program 358assembly 358assembly language 314, 358asset manager 159assignment 264assistant 71asymmetric digital subscriber line (ADSL) 111asynchronous transmission 384A-to-D (analog-to-digital) converter 223Atlas 184ATM (automatic teller machine) 81attachment 122–123attack 54attack, decay, sustain, release (ADSR) 54attribute 91audio streaming 38, 57–58 see also soundaudio controller 59audit trail 77authentication 75authoring language 316–317authoring tool 316authorisation 75authorisation code 168

436

automated reader 191–192automatic 183automatic recalculation 87Automatic Repeat Request (ARQ) 388automatic teller machine (ATM) 81automation 145auxiliary memory 193AVCHD 45AVCIntra 45

backbone 134, 135backdoor Trojan 172background job 364backing store 193, 194, 195backlit screens 212backup 81–82backup file 343Backus-Naur Form (BNF) 317–318backward compatible 239badging 187bandwidth 387bank switching 371bar code 78bar code reader 192bar code scanner 192base address 262basic input output system (BIOS) 356batch file 361batch processing 16batch total 76baud rate 223BCD (binary coded decimal) 336BD (Blu-ray disc) 199Bebo 127benchmark 238bespoke system 239beta testing 240–241big-bang 233binary coded decimal (BCD) 336binary digit 12binary logic 394binary notation 334, 337binary operator 287–288binary search 349binary tree 326bio-informatics 179biometric 167BIOS (basic input output system) 356bistable 381–382bit (BInary digiT) 12 start bit 384 stop bit 384bit map 202bitmapped graphics 39–40bits per second (bps) 223BitTorrent 125black box 299blind carbon copy 122block (data transfer) 202block (programming) 285block (spreadsheet) 86block diagram 246block structured language 285blocked 304blocking factor 329blog 120blogger 120blogging 120Blu-ray disc (BD) 199Bluetooth 143BNF (Backus-Naur Form) 317–318body text 34

bold 27bold italic 27bomb 305bookmark 118Boole, George 394Boolean algebra 394Boolean data 331Boolean operator 103, 288Boolean values 394boot 356boot file 356booting 356booting up 356bootscript 356bootstrap 356bot 118bottom-up programming 243bounce 122bps (bits per second) 223Bps (bytes per second) 223branch 276, 325break line break 29 page break 29breaking 274breakpoint 303bridge 143broadband 111, 387 mobile broadband 112browser 118bubble jet printer 216bubble sort 346bucket 202buffer 372–373 circular buffer 328 print buffer 372–373buffering 372bug 301bursting 217bus 367, 372bus interface 367bus network 132, 133business analyst 157by reference 282, 283by value 282, 283byte 12 status byte 265bytes per second (Bps) 223

cable coaxial cable 221–222 copper cable 221 fibre optic cable 222 twisted pair cable 222cache (web pages) 119cache memory 194, 201–202CAD (computer aided design) 175–176CAD/CAM (computer aided design/ manufacture) 176CAL (computer-aided learning) 176call 280CAM (computer-assisted manufacturing) 176camcorder 44camera digital camera 43 digital video camera 44carbon copy 122card compact flash card 44 credit/debit card 81 expansion card 378 interface card 378 memory card 200

SD card 200 smart cart 191 swipe card 167, 191 video capture card 45 video card 211 xD card 44card encoder 191card reader 191caret 65carrier board 378Carrier Sense Multiple Access/ Collision Detection (CSMA/CD) 392

carrier signal 389carrier wave 389carry flag 265cascading stylesheets (CSS) 33, 322case 26–27CASE (computer-aided software engineering) tools 245case statement 276cash dispenser 81cathode ray tube (CRT) 210CBT (computer-based training) 176CCITT (Comité Consultatif International Téléphonique et Télégraphique) 114

CD-R (compact disk recordable) 199CD-ROM (compact disk read-only memory) 199CD-ROM server 138CD-RW (compact disk rewritable) 199cell (memory) 195cell (spreadsheet) 86central node 134central processing unit (CPU) 366, 367–368central processor 367centred tab 29centred text 31certification authority 164change tracking 23channel 17 alpha channel 38 colour channel 38 music channel 60channel number 17character 324character code 324character data 331character printer 213, 214–215character recognition magnetic ink 79 optical 79–80character set 324character styles 32characters per second (cps) 223chat 126chat room 126check box 67check digit 76checksum 77child nodes 326chip 381Chrome 118cipher 177circuit switching 385circular buffer 328circular queue 328CISC (Complex Instruction Set Computer) 368class 261class diagram 256, 258class library 261

437

clicking 65client side 112–113client station 139client-server network 137client-server relationship 137clip art 43clipboard 18clock 378 real-time clock 381clock mark 79clock rate 378clock track 79closed loop feedback 145closed subroutine 281cloud computing 123cloud, the 196cluster 134cluster controller 134CMI (computer-managed instruction) 176CML (computer-managed learning) 176CMOS (complementary metal oxide semiconductor) 200CMS (colour management system) 207–208CMYK model 207CNC (computer numeric control) 146coaxial cable 221–222code 263 absolute code 270 ASCII code 324, 433–435 authorisation code 168 bar code 78 character code 324 intermediate code 314 machine code 314 micro-code 374 MIDI code 58 object code 359 position independent code 270 program code 263 pseudo-code 264, 291, 296 QR code 78, 79 relocatable code 270 SMPTE code 55 source code 359 Universal Product Code 78code breaking 177code generation 360codec 45coder 157coding 169cognitive science 150cold start 306collating sequence 324collision 343collision detection 392colour channel 38colour correction 38colour management 207–208colour management system (CMS) 207–208colour model 206–207colour palette 206colour printer 212colour separation 208column 86Comité Consultatif International Téléphonique et Télégraphique (CCITT) 114

command file 361command line interface 69command line interpreter 361

command sequence 69commissioning 238–239Common User Access (CUA) 365communications protocol 387–388compact disk read-only memory (CD-ROM) 199compact disk recordable (CD-R) 199compact disk rewritable (CD-RW) 199compact flash card 44compatibility 239compilation 360compilation error 301compiler 359–360complementary metal oxide semiconductor (CMOS) 200complementation 335–336completed 305Complex Instruction Set Computer (CISC) 368complex type 338composite key 330compress 35compression data compression 349–350 image compression 35–36, 37computer 4 analog computer 184 Complex Instruction Set (CISC) 368 desktop computer 185 digital computer 184–186 fifth-generation 184 first-generation 184 fourth-generation 184 host computer 140 hybrid computer 184 laptop computer 186 mainframe 186 minicomputer 186 notebook computer 186 personal computer 185 portable computer 186 quantum computer 187 Reduced Instruction Set (RISC) 368 second generation 184 stand-alone computer 186 supercomputer 186 tablet computer 185, 186 third-generation 184computer abuse 160, 164computer aided design/manufacture (CAD/CAM) 176computer animation 44computer bureau 5computer conferencing 126computer disk 196computer engineer 159computer engineering 155computer generations 183–184computer graphics 38computer hygiene 172computer misuse 164Computer Misuse Act 1990 160–161, 164computer modelling 106computer numeric control (CNC) 146computer operator 159computer science 155computer service engineer 159computer simulation 105–107computer system 4computer-aided design (CAD) 175–176

computer-aided draughting 175computer-aided learning (CAL) 176computer-aided software engineering (CASE) tools 245computer-assisted manufacturing (CAM) 176computer-based music system 61computer-based training (CBT) 176computer-managed instruction (CMI) 176computer-managed learning (CML) 176computing 4computing power 185concurrent thread 363concurrent user licence 173condensed type 209condition-controlled loop 274–275conditional 276configuration 4configuration management 239configuration manager 159connector symbol 292consistency 162constant 289constructor 261contactless technology 81context sensitive help 73continuation symbol 292continuous stationery 217control 144–147control character 324control panel 18control structure 272control total 76control unit 369controller 139 audio controller 59 cluster controller 134 musical instrument controller 59 network controller 139 sound controller 59conversational interface 69conversational mode 70cookies 119copper cable 221copy protection 173copyright 172–174core dump 303corrective maintenance 268correspondence quality 209corruption 349count-controlled loop 273courtesy copy 122CPM (Critical Path Method) 236cps (characters per second) 223cps (cycles per second) 50CPU (central processing unit) 366, 367–368crash 305 head crash 197 system crash 305crawler 118CRC (cyclic redundancy check) 77credit card 81critical path 236Critical Path Analysis 236–237Critical Path Method (CPM) 236cross-assembler 259cross-compiler 360cross-referencer 300cross-referencing 24CRT (cathode ray tube) 210cryptanalysis 177

438

cryptography 177 public key cryptography 169–170CSMA/CD (Carrier Sense Multiple Access/Collision Detection) 392CSS (cascading stylesheets) 33, 322CUA (Common User Access) 365cursor 64–65cursor movement key 65customise 13–15customised application 240customised system 239–240cut and paste 18cyber café 112cybernetics 151cyberspace 111cycle 373cycle time 373cycles per second (cps) 50cyclic redundancy check (CRC) 77cyclic shift 376cylinder 196, 197CYMK 207

D-to-A (digital-to-analog) converter 223daisy wheel printer 213data 323 alphanumeric data 331 Boolean data 331 character data 331 date data 331 inconsistent data 162 logical data 103, 331 personal data 163 raw data 350 sample data 331 scrambled data 168 sound data 331 string data 331 test data 299 video data 331data bus 372data capture 78, 145data centre 131data compression 349–350data consistency 162data controller 158, 162data description language (DDL) 94data dictionary 92data directory 92Data Encryption Standard (DES) 169data entry staff 158data file 330, 343–344data filter 103data flow diagram (DFD) 247–248data glove 147data integrity 162data logging 145Data Manipulation Language (DML) 102data member 261data mining 104data model 91data modelling 99–101data preparation 75data privacy 162data processing (DP) 74–75data processor 5data protection 161–162Data Protection Act 1998 160, 162–163data representation 323–331 numeric data 332–338data retrieval 91

data security 161–170data structure 325data subject 162data terminator 271data transmission 384data transmission rate 223data type 330–331 numeric data type 338 user-defined data type 331data warehouse 104data-processing manager 158database 90 distributed database 92 hierarchical database 92, 93 object-oriented database 93–94 relational database 94database administrator (DBA) 158database management system (DBMS) 91, 92database manager 158database server 138datagrams 385date data 331daughterboard 378DBA (database administrator) 159DBMS (database management system) 91, 92DDL (data description language) 94DDoS (distributed denial of service) 129deadlock 305deadly embrace 305debit card 81debugger 300debugging 300debugging tools 300decay 54decimal tab 29deciphering 169decision box 293decision support specialist 158decision support system (DSS) 178decision symbol 293decision table 291, 292declaration 285declarative language 315decoding 169decollate 217decommissioning 238–239decorative font 26decryption 168, 169decryption key 168default 15default option 15, 266default value 15defragmentation 365deinstall 19delta compression 36demodulation 391denary notation 334, 336denial of service (DoS) 129dependencies 238derived class 261DES (Data Encryption Standard) 169design modular design 243 object-oriented design 243 systems design 232design methodology 231desktop 63desktop computer 185desktop publishing (DTP) 21–22destructor 261DEUCE 184

developer 157 website developer 158development cycle software development cycle 230–231 system development cycle 230developmental testing 240–241device 5DFD (data flow diagram) 247–248DHTML (dynamic HTML) 319diagnostic aids 300diagnostic program 300dial-up connection 111dialogue box 66–67dictionary 24differential backup 81digital 183digital camera 43digital camera storage 44digital certificate 164–165digital computer 184–186digital plotter 217digital sampler 223digital sensor 146digital signal 222digital signature 164digital sound system 61digital still imaging 43–44digital subscriber line (DSL) 111digital synthesiser 59digital versatile disk (DVD) 199digital video 44–48digital video camera 44digital video disk (DVD) 199Digital Video (DV) format 45digital-to-analog (D-to-A) converter 223digitising 223dimension 327dip switch 382direct access 342direct addressing 370direct changeover 233direct memory access (DMA) 371directive 289directory 12, 68 data directory 92 root directory 68directory file 68disassembler 361disinfection 172disk 196 compact disk 199 computer disk 196 digital versatile disk 199 hard disk 196 installation disk 173–174 key disk 174 magnetic disk 196 RAM disk 201 silicon disk 201disk access time 197disk array 197disk caching 202disk drive 196disk format 198disk formatting 198disk map 202disk operating system (DOS) 357disk pack 196, 197disk tracks 196disk verification 198display 210–212display adapter 211display order 101

439

display screen 210distributed database 92distributed denial of service (DDoS) 129distributed networking 131distributed processing 139dithering 206, 207DMA (direct memory access) 371DML (Data Manipulation Language) 102do loop 273document 9 turnaround document 81document checking 23–24document imaging 80document reader 80document scanner 80documentation 234 hardware documentation 72–73 maintenance documentation 234 program documentation 234, 291 project documentation 235 software documentation 71–72 systems documentation 234 technical documentation 234 user documentation 71domain name 114 geographical identifiers 430–432domain name servers 114dongle 173DoS (denial of service) 129DOS (disk operating system) 357dot matrix printer 213dot pitch 208dots per inch (dpi) 208, 209double buffering 372double clicking 65double entry verification 76double precision 338down time 305download 350downward compatible 239DP (data processing) 74–75dpi (dots per inch) 208, 209draft quality 209drag 67drag-and-drop editing 67DRAM (dynamic random access memory) 201‘drawing on the fly’ 39drawing package 42driver 8 printer driver 209drop-down menu 65dry run 301DSL (digital subscriber line) 111DSS (decision support system) 178DTP (desktop publishing) 21–22dummy variable 287dump 303duplex 384DV (Digital Video) format 45DVCam 45DVCProHD 45DVD (digital versatile disk) 199dye sublimation printer 216dynamic compiler 360dynamic HTML (DHTML) 319dynamic IP address 114dynamic random access memory (DRAM) 201dynamic variables 286

E ink 210EAN (European Article Number) 78

EAROM (electrically alterable read-only memory) 201ease of maintenance 244ease of use 244echo 384ECMA (European Computer Manufacturers’ Association) symbols 291

ecommerce 127–128editable text 80editing 23 drag-and-drop editing 67 offline editing 46 online editing 48 photo editing 40–42 real-time editing 48 screen editing 70 video editing 46–48EDSAC 184EDVAC 184EEPROM (electrically erasable programmable read-only memory) 201

EFT (electronic funds transfer) 80EFTPOS (electronic funds transfer at point of sale) 81electrically alterable read-only memory (EAROM) 201electrically erasable programmable read-only memory (EEPROM) 201electromagnetic interference (EMI) 391electronic funds transfer at point of sale (EFTPOS) 81electronic funds transfer (EFT) 80electronic mail 120–122electronic money 80electronic signature 164else 276em 26email 120–121email address 122email virus 171embedded keyboard 189embedded object 16embedded system 4EMI (electromagnetic interference) 391emphasis 27emulation 107emulator 107en 26encapsulation 260enciphering 169encoding 169encryption 168–169encryption key 168end of file (EOF) marker 329end-user licence agreement (EULA) 172endnote 32ENIAC 184entity 91entity-relationship 249entity-relationship diagram 249envelope 53–54EOF marker (end of file marker) 329EOR (Exclusive-OR) gate 400epayment 80–81EPROM (erasable programmable read-only memory) 201EQ (equivalence) gate 400equivalence (EQ) gate 400

erasable programmable read-only memory (EPROM) 201error 298, 301 compilation error 301 execution error 301 linking error 301 logical error 301 program syntax error 301 rounding error 351 run-time error 301 statement syntax error 301 structure error 301 syntax error 301 truncation error 351error message in applications 71 in programming 301escaping 274Ethernet 141Ethernet hub 141Eudora 122EULA (end-user licence agreement) 172European Article Number (EAN) 78European Computer Manufacturers’ Association (ECMA) symbols 291event 264–265 mouse event 189exclusive-NOR (XNOR) gate 400–401exclusive-OR (XOR) gate 400execute phase 369execution 299execution error 301executive program 363exit 280expansion card 378expansion slot 378expert system 151–152, 153exponent 334export 18extensible language 315–316external review 235extranet 140–141

Facebook 127facilities management 4FALSE 103fan-fold paper 217FAQ (Frequently Asked Questions) 126FAT (file allocation table) 202father file 344fault tolerance 145favourite 118FDM (frequency-division multiplexor) 221feasibility study 231–232feedback 145 haptic feedback 148 open/closed loop feedback 145FEP (front-end processor) 186fetch phase 369fetch-execute cycle 369fibre optic cable 222field (data) 329, 330 key field 329, 330 response field 70field (machine code) address field 267 operand field 267 operation code field 267field locking 345field name 329, 330

440

field type 331 numeric field type 338FIFO (first in, first out) 328fifth-generation computer 184file 9 archive file 343 backup file 343 batch file 361 boot file 356 closing 339 command file 361 creating 339 data file 330, 343–344 deleting 339 directory file 68 father file 344 flat file 92, 93 grandfather file 344 index file 344 journal file 77, 343 listing file 301 master file 343 opening 339 random access file 340 random file 340 README file 73 reference file 343 sequential file 340 serial file 340 son file 344 temporary file 344 transaction file 344 ZIP file 349file access 341–342file allocation table (FAT) 202file associations 12file locking 344–345file lookup check 76file operations 344file server 137file sharing, peer-to-peer 124–125file structure 339–341file transfer 124File Transfer Protocol (FTP) 124file type 9–12filename 9filename extension 10–12, 426–429filter 8–9 data filter 103 graphics filter 8 spam filter 128finance package 175find 23firewall 165, 166Firewire 388first in, first out (FIFO) 328first normal form (1NF) 95, 96–97first-generation computer 184fixed-format record 329fixed-length record 329fixed-point representation 334, 335flag 265flame 126flash drive 200flat file 92, 93flat-bed plotter 216flat-bed scanner 192flexibility 244Flickr 127flip-flop 381–382float time 237float type 338floating point unit 366floating-point representation 334–335

flow line 252, 291flowchart 252–254 program flowchart 291, 295–296, 297 system flowchart 249–251fly by wire 145–146FM (frequency modulation) 55, 390folder 12, 68font 25–26, 209–210font cartridge 209font size 26footer 29footnote 32footprint 187for loop 273, 289forecasting 107foreground job 364foreground/background processing 364formal methods 241formal parameter 282formal specification 241format for printing 269–270 record format 328 report format 101format check 76formatting 198forms dialogue interface 70formula 86forward 122fourth-generation computer 184fourth-generation language (4GL) 309fragmentation 365 message fragmentation 385frame (communications) 389frame (display) 211Freedom of Information Act 2000 163Freenet 125freeware 173frequency 50frequency modification 54–55frequency modulation (FM) 55, 390frequency shifting 54frequency-division multiplexor (FDM) 221Frequently Asked Questions (FAQ) 126friction feed 217front-end processor (FEP) 186FTP (File Transfer Protocol) 124full backup 81full duplex 384full justification 31function (programming) 279function (spreadsheet) 86–87function key 189functional decomposition 243functional language 315functional specification 243fuzzy logic 154

Gantt chart 236garbage collection 365gate 394 logic gates 396–401gateway 143generic software 6genetic algorithm 153genetic programming 153geographical domain identifiers 430–432

geographical information system (GIS) 177gigabytes 12GIS (geographical information system) 177global positioning system (GPS) 177global variable 286goal seeking 88golf ball printer 213Google Video 127GPS (global positioning system) 177grammar checking 23grandfather-father-son files 344graph plotter 216–217graphical interfaces 63–68graphical user interface (GUI) 63graphics bitmapped graphics 39–40 computer graphics 38 low-resolution graphics 209 pixel graphics 211 raster graphics 211 turtle graphics 317 vector graphics 212graphics adapter 211graphics design applications 38–43graphics filter 8graphics pad 39graphics tablet 39, 40greyscale model 207GUI (graphical user interface) 63gutter 32

hacker 164hacking 164half duplex 384hand-held scanner 192handle 17handshake 223handwriting recognition 190–191haptic feedback 148hard copy 217hard disk 196hard disk drive 196hard space 28hard-wired logic 381hardware 5hardware documentation 72–73hardware platform 244harmonics 51, 52hash table 342hash total 77hashing 342–343hashing algorithm 340HCI (human-computer interaction/ interface) 63HD (high definition) digital video format 45–46HDTV (high definition TV) 393HDV 45head crash 197header 29, 389headset 148health informatics 179help desk 159help system 73hertz (Hz) 50heuristic program 265heuristics 152hex 336hexadecimal notation 336, 337hierarchical database 92, 93

441

high definition (HD) digital video format 45–46high definition TV (HDTV) 393high-level language 309–314high-resolution image 208high-speed link 388–389highlighting 64hit 348hit rate 348home banking 81home page 117host computer 140hot key 67–68hot line 159hotspot 112HTTP (HyperText Transfer Protocol) 113hub 134 Ethernet hub 141 switched hub 142hue saturation value 207human-computer interaction (HCI) 63human-computer interface 63hung 305hybrid computer 184hyperlink 117–118HyperText Mark-up Language (HTML) 319–321HyperText Transfer Protocol (HTTP) 113Hz (hertz) 50

I-beam cursor 65I/O (input/output) device 6IAB (Internet Architecture Board) 115IAR (instruction address register) 369IAS (immediate-access store) 195IBM 360 184IC (integrated circuit) 381ICL 1900 184icons 64ICT (information and communications technology) 3IDE (integrated development environment) 238identifier 288–289IDS (intrusion detection system) 166if statement 275–276IKBS (intelligent knowledge-based system) 151ikons 64ILS (integrated learning system) 176iMac 185image compression 35–36, 37image data formats 35–38image enhancement 42image scanner 192immediate addressing 370immediate mode 306immediate-access memory 193, 194immediate-access store (IAS) 195immersive virtual reality 147impact printer 213imperative language 314–315implementation 232–233import 18in-betweening 44inconsistent data 162incremental backup 82incremental plotter 217

index file 344index register 370index sequential access method (ISAM) 342indexed access 342indexed addressing 370indexing 24indirect addressing 370infection 171inference engine 152infinite loop 273–274infix notation 262information 323Information Commissioner 162information and communication technology (ICT) 3information flow diagram 247information management personnel 158information manager 158information officer 158information processing 3information retrieval 91information super highway 111information systems 155information systems engineer 157information systems engineering 242information technology (IT) 3, 155infrared communication 221inheritance 261initial sequence number (ISN) 392initial value 265initialise 265ink cartridge 216inkjet printer 213, 216input device 5, 188–189 automated input 191–192 manual input 189–191input symbol 292input/output (I/O) device 6input/output symbol 292–293insert 344inserting 17inspection 300install 19installation 233installation disks 173–174instance of the class 261instant messaging 125–126instruction machine-code instruction 267 macro instruction 283 micro-instruction 374 multiple-address instruction 267–268 one-address instruction 267 single-address instruction 267–268 two-address instruction 268instruction address register (IAR) 369instruction cycle 369instruction decoder 369instruction set 368–369int type 338integer 334integer type 338integrated circuit (IC) 381integrated circuit memory 200integrated development environment (IDE) 238integrated graphics package 41–42integrated learning system (ILS) 176

integrated manufacturing 146integrated package 6integrated program 6integrated programming environment 238Integrated Services Digital Network (ISDN) 388integrity 162integrity check 76intelligent knowledge-based system (IKBS) 151intelligent time division multiplexor 221interactive computing 69–70interactive processing 16interactive whiteboard 191interface (hardware) 366–367, 377–378, 379–380interface (user) command line interface 69 conversational interface 69 forms dialogue interface 70 graphical interfaces 63–68 graphical user interface 63 human-computer interface 63 man-machine interface 63 menu selection interface 64 user interface 63interface board 367, 378interface card 378interference 391–392interlace 46interleaving 365intermediate code 314International Standard Book Number (ISBN) 78International Telecommunications Union (ITU) 114–115internet 109–111Internet Architecture Board (IAB) 115internet café 112Internet Protocol (IP) 113Internet Protocol (IP) address 114internet server 138internet service provider (ISP) 111Internet Society 115interpreter 308, 360–361interrogating 102interrupt 374intranet 140intrusion detection system (IDS) 166inverse 397inverse video 64inverter 397IP datagram 385IP (Internet Protocol) 113IP (Internet Protocol) address 114ISAM (index sequential access method) 342ISBN (International Standard Book Number) 78ISDN (Integrated Services Digital Network) 388ISN (initial sequence number) 392ISO 7 386ISO 8859 324ISP (internet service provider) 111IT (information technology) 3, 155IT end-user 157IT practitioner 155–157IT user 157italic 27iteration 273

442

ITU (International Telecommunications Union) 114–115

Jackson Structured Programming (JSP) 231JCL (job control language) 364job 364 background/foreground job 364 print job 362job control language (JCL) 364job queue 364Joint Photographic Experts Group (JPEG) 36journal file 77, 343JPEG (Joint Photographic Experts Group) 36JSP (Jackson Structured Programming) 231jump 276jumper 382justification 30, 31

Karnaugh map 395KBS (knowledge-based system) 151Kermit 388kerning 28key (cryptography) decryption key 168 encryption key 168 private key 169 public key 169key (data file) 329–330 composite key 330 primary key 329 secondary key 330 sort key 329, 330key (keyboard) arrow key 65 cursor movement key 65 function key 189 hot key 67–68 quick key 67 short cut key 67key disk 174key escrow 165key field 329, 330key field order 329key frames 44key logger 128keyboard 189 music keyboard 49–50 touch-sensitive keyboard 190keyboard short cut 67keycard 167keyword 289kHz (kilohertz) 50kilobytes 12kilohertz (kHz) 50knowledge base 152, 317knowledge engineer 152knowledge-based system (KBS) 151

LA (linear arithmetic) 56label 285LAN (local area network) 132languages see programming languageslaptop computer 186laser printer 213, 216last in, first out (LIFO) 328latency 197, 382LATEX 23layers 40

LCD (liquid crystal display) 210, 212leading 27–28leaf node 326learning platform 177LED (light emitting diode) 210, 212left justification 31left-aligned tab 29length check 75LEO (Lyons Electronic Office) 184letter quality 209lexical analysis 360library 358 subroutine library 280library routine 358licence, software 172–173licence agreement 172life cycle software life cycle 230 system life cycle 228–229LIFO (last in, first out) 328light emitting diode (LED) 210, 212light sources 36line art 39line break 29line feed 217line speed 388–389linear arithmetic (LA) 56linear search 348–349link editor 361linked list 328linked object 16linked styles 32linker 361linking 361linking error 301linking loader 361Linux 358liquid crystal display (LCD) 210, 212list 326 linked list 328 sort list 101list box 66list server 123list-processing language 316listing 291listing file 301loader 361–362local area network (LAN) 132local variable 286location 195log in/on 166log off/out 167logging in/on 166logging off/out 167logic bomb 172logic circuit 381logic element 381logic engine 317logic gates 396–401 AND gate 398 EOR gate 400 EQ gate 400 NAND gate 399 NEQ gate 400 NOR gate 398–399 NOT gate 397 OR gate 397–398 XNOR gate 400–401 XOR gate 400logic programming language 315logic symbol 395logical data 103, 331

logical equivalence 395logical error 301logical operation 266–267logical operator 103, 288logical record 329logical shift 375logical value 103login script 357Logo 317look-up table 266lookup check 76loop 272–273 condition-controlled loop 274–275 count-controlled loop 273 do loop 273 for loop 273 infinite loop 273–274 nested loop 272 repeat … until loop 275 while loop 275loop network 133loose 28lossless (image compression) 36lossless (sound format) 57lossy (image compression) 36lossy (sound format) 57low-level language 314low-resolution graphics 209low-resolution image 208lower case 26LTE 112lurk 127Lyons Electronic Office (LEO) 184LZW algorithm 349

M&S stereo 53Mac OS 358machine architecture 366–367machine code 314machine cycle time 373machine intelligence 150machine readable 191machine-code instruction 267machine-code subroutine 280machine-oriented languages 314Macintosh 185macro 13, 283macro assembler 359macro instruction 283macro recording 13macro virus 171magnetic card encoder 191magnetic disk 196magnetic disk drive 196magnetic disk storage 195Magnetic Ink Character Recognition (MICR) 79magnetic stripe 191magneto-optical storage 196mail electronic mail 120–122 snail mail 120mail server 138mailbox 122mailmerge 25main store 195mainboard 378mainframe computer 186maintenance 233–234 ease of 244 program maintenance 268maintenance documentation 234maintenance engineer 159

443

malicious code 171–172malware 128MAN (metropolitan area network) 132man-machine interface (MMI) 63managed learning environment (MLE) 177managed services 4management information systems (MIS) 177–178mantissa 334manual recalculation 87MAR (memory address register) 369mark-up languages 309, 318–322mask 266masking 376–377mass storage 195master file 343mathematical applications 178matrix printer 214–215maximum transmission unit (MTU) 386MBR (memory buffer register) 369–370MDR (memory data register) 370media 5media converter 142medical informatics 179megabytes 12member function 260member procedure 260memory 193–195, 370–371 auxiliary memory 193 cache memory 194, 201–202 immediate-access memory 193, 194 integrated circuit memory 200 permanent memory 194, 196 programmable memory 195 random access memory 194, 201 read-only memory 194–195, 201 semiconductor memory 200 serial-access memory 194 virtual memory 371 volatile memory 194, 196memory address register (MAR) 369memory buffer register (MBR) 369–370memory card 200memory cell 195memory data register (MDR) 370memory dump 303memory location 262memory management 370–371memory management unit (MMU) 371memory map 202memory module 378memory stick 44Memory Stick (MS) 200menu 65menu bar 65menu selection interface 64merge 345, 346merge sort 347message fragmentation 385message queuing 385message switching 385meta language 317–318metadata 94–95METAFONT 23metal oxide semiconductor (MOS) 200

method 260–261metric 238metropolitan area network (MAN) 132MICR (Magnetic Ink Character Recognition) 79micro 185micro-code 374micro-instruction 374micro-program 374Microcom Network Protocol (MNP) 388microprocessor 366, 368Microsoft Internet Explorer 118Microsoft Outlook 122Microsoft Windows 357microwave transmission 221MIDI channel 58MIDI code 58MIDI (Musical Instrument Digital Interface) 58MIDI standard 58migrate 242millions of instructions per second (MIPS) 373MIME (Multi-purpose Internet Mail Extensions) 122mini-tower 185minicomputer 186miniDV 45MIPS (millions of instructions per second) 373MIS (management information system) 177–178mixing desk 60MLE (managed learning environment) 177MMI (man-machine interface) 63MMU (memory management unit) 371mnemonic 268MNP (Microcom Network Protocol) 388mobile broadband 112mobile computing 112model 106modelling 106modem (MOdulator-DEModulator) 219–220moderated newsgroups 127modular design 243modulation 389–391MOdulator-DEModulator (MODEM) 219–220module 243 example 294–297monitor 204–205, 210monitor program 363mono 51monochrome printer 212monophonic 51monospace font 26, 210Monte Carlo method 107–108morphing 44MOS (metal oxide semiconductor) 200motherboard 377–378Motion Picture Experts Group (MPEG) 36mouse 189mouse button 189mouse event 189mouse mat 189mouse pointer 64

Mozilla Firefox 118Mozilla Thunderbird 122MPEG (Motion Picture Experts Group) 36MS (Memory Stick) 200MS-DOS 357MTU (maximum transmission unit) 386multi-access system 16Multi-purpose Internet Mail Extensions (MIME) 122multi-tasking 363multi-threading 363multi-timbral synthesiser 59multi-user licence 173multicore 368multimedia 4multipart stationery 217multiple-address instruction 267–268multiplexor 220–221multiprocessor system 187multiprogramming 363music channel 60music composition software 178music keyboard 49–50music synthesiser 58–59music workstation 61musical instrument controller 59Musical Instrument Digital Interface (MIDI) 58MySpace 127

name table 362NAND gate 399narrow band 387negative numbers 335–336NEQ (non-equivalence) gate 400nested folders 12nested loop 272net etiquette 127Net, the 109–111netiquette 127network 130–131 bus network 132, 133 client-server network 137 local area network 132 loop network 133 metropolitan area network 132 neural network 150–151 peer-to-peer network 136–137 ring network 133, 134 star network 134, 135 token ring network 134, 136 virtual local area network 143 virtual network 136 wide area network 132network accounting software 140network controller 139network manager 159network operating system 139–140network privileges 167network relationship 137network station 139network terminal 139network topology 132–134neural net 150neural network 150–151newsgroup 126–127next instruction register 369nexus 134node 325–326

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noise 43, 389non-breaking space 29non-equivalence (NEQ) gate 400non-immersive virtual reality 147non-volatile memory 196NOR gate 398–399normal form 95–99normalise 337–338NOT gate 397NOT operation 103, 266notebook computer 186notepad 18Novell NetWare 140number cruncher 178numbers negative numbers 335–336 real numbers 334numeric control 146numeric data, representation 332–338numeric data type 338numeric field type 338numeric keypad 189numeric overflow 350numeric variable type 338

object 260 embedded object 16 linked object 16object class 261object code 359object linking and embedding (OLE) 16object program 359object-oriented database 93–94object-oriented design 243object-oriented programming language 315object-oriented programming (OOP) 260OCR (Optical Character Recognition) 79–80octal notation 336, 337OEM (original equipment manufacturer) 187offline editing 46offline processing 17offset 262OLE (object linking and embedding) 16OMR (optical mark recognition) 78–79one-address instruction 267one-dimensional array 326one-way functions 170one’s complement 336online editing 48online processing 17OOP (object-oriented programming) 260open loop feedback 145open subroutine 281open system 386–387Open Systems Interconnection (OSI) 386–387Opera 118operand 267operand field 267operating system (OS) 8, 357–358 network operating system 139–140operation box 293operation code field 267operation symbol 293operational mode 16–17

operator 287–288 arithmetic operator 288 binary operator 287–288 Boolean operator 103, 288 logical operator 103, 288 relational operator 288 string operator 288 unary operator 288Optical Character Recognition (OCR) 79–80optical disk storage 195optical fibre 222optical mark recognition (OMR) 78–79optical storage 198–200OR gate 397–398OR operation 103, 266original equipment manufacturer (OEM) 187orphan 31–32OS (operating system) 8, 357–358OSI (Open Systems Interconnection) 386–387output 204 colour 206–208 display 210–212 printing 212–218 quality 208–210output device 5, 204–206output symbol 292outsourcing 4, 157overflow 350overflow area 343overflow data 343overflow flag 265overlay 268–269overloading 261–262overtyping 17overwrite 344overwriting 17ownership 168

PABX (private automatic branch exchange) 220packet 385packet switching system (PSS) 385packing 270page 371 home page 117 web page 115page break 29page description language 218page fault 371page feed 217page layout 22page makeup 22page printer 214–215page turn 371paging 371painting package 42PAL (Phase Alternating Line) 212palette 206pane 64Pantone 208paper feed mechanism 217paper tape 146paper tape punch 146paper tape reader 146paragraph styles 32parallel data transmission 384parallel processing 372parallel running 233parameter 282parameter passing 282, 283parasitic virus 171

parent node 326parental controls 129parity check 77park 197parsing 362passive device 146passive system 144password 167password protection 168paste 18patch 303pattern recognition 151payload 171PBX (private branch exchange) 220PC (personal computer) 185PCM (pulse code modulation) 391PD (phase distortion) 56peer review 235peer-to-peer file sharing 124–125peer-to-peer network 136–137peer-to-peer relationship 137Pegasus 184Pegasus Mail 122pen drive 200perfective maintenance 268peripheral 5–6permanent memory 194, 196personal computer (PC) 185personal data 163personal firewall 165personal identification device (PID) 167personal identification number (PIN) 167phase 51Phase Alternating Line (PAL) 212phase distortion (PD) 56phase modulation 391phased implementation 233phishing 129phoneme 179photo CD 44photo editing 40–42photo printer 43photo-quality printer 216physical record 329pica 26Picasa 127PID (personal identification device) 167pilot running 233pin feed 217PIN (personal identification number) 167pin printer 213pipelining 376piracy 173–174pitch 50, 210pivot table 88–89pixel 205, 211pixel graphics 211PLA (programmable logic array) 382platform 244platter 196plotter 216–217plug-in software 358podcast 125point 26point of presence (PoP) 113point-of-sale (POS) terminal 139pointer (programming) 345pointer (user interface) 64polling 377polymorphism 262

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polyphony 59pop 328PoP (point of presence) 113pop-up menu 65POP3 (Post Office Protocol 3) 113port 17port number 17portability 244portable computer 186portable storage device 200portal 120POS (point-of-sale) terminal 139position independent code 270Post Office Protocol 3 (POP3) 113post-mortem routine 300postfix notation 262posting 126postmaster 123PostScript 218pre-printed stationery 217–218prefix notation 262prefixes 423–425presence check 75presentation order 101presentation package 178–179pressure control 190pressure pad 190pressure switch 190pretty printer 269–270preview 24–25primary key 329primary store 195print buffer 372–373print cartridge 216print head 212print job 362print preview 24print quality 209print queue 362print spooler 362PRINT USING 269printer 206, 212–213 bubble jet printer 216 character printer 213, 214–215 colour printer 212 daisy wheel printer 213 dot matrix printer 213 dye sublimation printer 216 golf ball printer 213 impact printer 213 inkjet printer 213, 216 laser printer 213, 216 monochrome printer 212 page printer 214–215 photo printer 43 photo-quality printer 216 pin printer 213 pretty printer 269–270 thermal printer 213 thermal wax printer 216printer driver 209printer font 209printer resolution 209printer server 138printer spooler 362printf 269printing 212–218printout 217privacy 162private automatic branch exchange (PABX) 220private branch exchange (PBX) 220private key 169privileges 167

problem-oriented languages 309procedural languages 315procedure 279process 241process box 293process control 146process state 304–305process symbol 293–294processing batch processing 16 distributed processing 139 foreground/background processing 364 interactive processing 16 offline processing 17 online processing 17 parallel processing 372 tele-processing 16 transaction processing 16processing mode 363–364processor 367 front-end processor 186 sound processor 59–60processor cycle time 373productivity tool 6profile 71program 284 applications program 6 assembler program 358 diagnostic program 300 executive program 363 heuristic program 265 integrated program 6 micro-program 374 monitor program 363 object program 359 re-entrant program 282–283 self-documented program 271, 290 source program 359 supervisor program 363 systems program 356 utility program 358program algorithm 263, 264program code 263program counter 369program documentation 234, 291program execution 299program flowchart 291, 295–296, 297program flowchart diagram 291program flowchart symbol 291–294program library 358program listing 291program maintenance 268program statement 285program suite 284program syntax errors 301programmable 183programmable logic array (PLA) 382programmable memory 195programmable read-only memory (PROM) 201programmer 157 applications programmer 157 systems programmer 157programming bottom-up programming 243 genetic programming 153 object-oriented programming 260 structured programming 243 top-down programming 243

programming languages 307–317 levels of 309–314 specialised 316–322 types 314–316 see also specific languagesprogressive scan 46project 234project documentation 235project lifetime 235project management 235project management software 236project proposal 235project review 235project schedule 235project team leadership 235Prolog 317PROM (programmable read-only memory) 201prompt 70propagation delay 382property 261proportional font 26proportional spacing 210proprietary 187protected software 173protocol communications protocol 387–388 File Transfer Protocol 124 HyperText Transfer Protocol 113 Internet Protocol 113 Microcom Network Protocol 388 open system protocol 386–387 Post Office Protocol 3 113 remote desktop protocol 136 Simple Mail Transfer Protocol 113 Transmission Control Protocol 388 Transmission Control Protocol/ Internet Protocol 141 Voice over Internet Protocol 125prototype 241prototyping 241proxy server 165–166pseudo-code 264, 291, 296pseudo-random number generator 108PSS (packet switching system) 385PSTN (public switched telephone network) 392PTO (public telephone operator) 392public domain software 173public key 169public key cryptography 169–170public switched telephone network (PSTN) 392public telephone operator (PTO) 392pull 328pull-down menu 65pulse code modulation (PCM) 391push 328

QBE (Query By Example) 102QR (quick response) code 78, 79quality, output 208–210quality controller 158quantum computers 187quarantine 172query 102–103Query By Example (QBE) 102query language 102

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queue 328 circular queue 328 job queue 364 print queue 362quick key 67quick response (QR) code 78, 79quick sort 347–348qwerty keyboard 189

RAD (Rapid Application Development) 231radio frequency identification device (RFID) 78radio frequency interference (RFI) 392RAID (redundant array of inexpensive/independent disks) 197

RAM (random access memory) 194, 201 video RAM 211RAM disk 201random access 342random access file 340random access memory (RAM) 194, 201 video RAM 211random file 340random number generation 108range 86range check 75Rapid Application Development (RAD) 231raster graphics 211raw data 350RDP (remote desktop protocol) 136re-entrant program 282–283read 344read-only access 345read-only memory (ROM) 194–195, 201read/write head 197README file 73ready 304real number 334real type 338real-time clock 381real-time editing 48real-time entry 61real-time system 16Really Simple Syndication (RSS) 120reboot 356recalculation 87receipt 122record 328–329, 330record format 328record locking 345record number 342recovery 305–306recursive subprogram 281RED 45redirection 114Reduced Instruction Set Computer (RISC) 368redundancy 36redundant array of inexpensive/ independent disks (RAID) 197reference file 343refresh (memory) 201refresh (screen) 210refresh rate 210register 369–370 address register 369 arithmetic register 373

index register 370 instruction address register 369 memory address register 369 memory buffer register 369–370 memory data register 370 next instruction register 369 sequence control register 369 shift register 374registry 357relation 91relational database 94relational operators 288relationship 91relative address 262relative reference 88release 54reliability 244relocatable code 270relocation 270remote access 16remote desktop protocol (RDP) 136remote job entry (RJE) 364render 36repeat ... until loop 275repeater 142replace 23replacement rules 317replication 87–88reply 122report 101report definition 101report format 101report generator 102report layout 101request verification 203requirements specification 242–243, 245reserved word 289reset 306resolution 208–209response field 70restore 82return 280reverse engineering 242Reverse Polish notation 263RFI (radio frequency interference) 392RFID (radio frequency identification device) 78RGB colour model 207right justification 31right-aligned tab 29ring network 133, 134 token ring network 134, 136RISC (Reduced Instruction Set Computer) 368risk manager 157river 28RJE (remote job entry) 364robot (mechanical device) 146robot (program) 118robot arm 146robotics 151robustness 244rogue terminator 271rogue value 271ROM (read-only memory) 194–195, 201root directory 68root node 326rotation 376round-robin 365rounding 351rounding error 351router 142

routine 280 library routine 358 post-mortem routine 300routing 143row 86RSA algorithm 170RSS (Really Simple Syndication) 120rule 29rule base 152run 302run-time 302run-time error 301run-time system 303running 304

SAA (Systems Application Architecture) 365Safari 118sample data 331sampler 223sampling of data 145 sound sampling 49, 55, 56sampling rate 55, 56sampling resolution 55sans serif font 26satellite 221satellite navigation 177satnav 177scalable 209scams 129scanner 192scheduling 365schema 94scientific measurement and analysis 178scope 286SCR (sequence control register) 369scrambled data 168screen 210screen button 67screen dump 303screen editing 70screen font 209screen refresh 210screen resolution 208screen saver 68screen verification 76script 13script language 13scroll bar 18scroll wheel 189scrolling 18SD (Secure Digital) card 200SDSL (symmetric digital subscriber line) 111search 348–349search engine 118–119searching 102Second Life 127second normal form (2NF) 97–98, 101second-generation computer 184secondary key 330secondary store 195secret message 177sector 198Secure Digital (SD) card 200Secure Electronic Transaction (SET) 165Secure Socket Layer (SSL) 165security data security 161–170 measures 161

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security administrator 158seek time 197segment 365segmentation 365selecting 102selection sort 347self-documented program 271, 290semantic net 153semantic web 117semantics 284semiconductor memory 200sensitive personal data 163sensor 146sentence case 27sequence control register (SCR) 369sequence diagram 255, 256sequence number 392sequencer 60–61sequential access 341–342sequential file 340serial access 341serial data transmission 384serial file 340serial search 348–349serial-access memory 194serif font 26server 137–138 application server 138 CD-ROM server 138 database server 138 domain name server 114 file server 137 internet server 138 list server 123 mail server 138 printer server 138 proxy server 165–166 terminal services server 138 web server 138server farm 131–132server side 113service engineer 159service pack 303service-oriented architecture 231servo 145servo mechanism 145set 265SET (Secure Electronic Transaction) 165SGML (Standard Generalised Mark-up Language) 319shareware 173sheet-feed scanner 192shell 152shift 267, 374–376shift register 374short cut key 67short cut menu 65shrink-wrapped software 242sign and magnitude 335sign and modulus 335signal 389 analog signal 222–223 carrier signal 389 digital signal 222signal amplifier 222signal booster 222signal converter 222–223signal level 222signal routing 384–385signal-to-noise ratio 389silicon disk 201Simple Mail Transfer Protocol (SMTP) 113simplex 384

simulation 105–107single buffering 372single precision 338single stepping 300single switch device 190single thread 363single-address instruction 267–268single-tasking 363single-user licence 173site licence 173Skype 125slanting 27slot 367, 378small capitals 27smart card 191smartmedia 44smartphone 185, 186SMPTE (Society of Motion Picture and TV Engineers) codes 55SMTP (Simple Mail Transfer Protocol) 113SNA (Systems Network Architecture) 365snail mail 120social networking 127Society of Motion Picture and TV Engineers (SMPTE) codes 55soft space 28software 6 generic software 6 plug-in software 358 protected software 173 public domain software 173 shrink-wrapped software 242 system software 8–9, 355 unprotected software 173software copyright 172–173software development cycle 230–231software documentation 71–72software engineer 157software engineering 155, 242software library 358software licence 172–173software life cycle 230software metric 238software piracy 173–174software support staff 159software upgrade 242solid-state drive (SSD) 198son file 344sort key 329, 330sort list 101sorting 345–348sorting algorithm 346sound 49 characteristics 50–53 devices 58–61 processing 53–58sound controller 59sound data 331sound format 57sound generation 55sound generator 59sound mixer 60sound processor 59–60sound sampling 49, 55, 56sound source 59sound synthesis 55–57source code 359source language 359source program 359space 28–29spam 128spam filter 128

specification 242–243speech recognition 191speech recognition software 191speech synthesis 179speech synthesiser 179spell checking 23spiral model 229spooling 362spot colour 207spreadsheet 83–86spyware 128SQL (Structured Query Language) 102SSADM (Structured Systems Analysis and Design Methodology) 231

SSD (solid-state drive) 198SSL (Secure Socket Layer) 165stack 328stack overflow 350stakeholders 235stand-alone computer 186standard function 279–280Standard Generalised Mark-up Language (SGML) 319star network 134, 135start bit 384start/stop box 294start/stop symbol 294state diagram 256, 258statechart diagram 256, 258statement syntax errors 301static IP address 114static random access memory 201static variables 286station 139stationery 217–218statistical applications 178statistical multiplexor 221status bar 19status byte 265status word 265step mode 300step-time entry 61stepper/stepping motor 147stepwise refinement 243stereo 51stereo image 51stereophonic sound 51–53stop bit 384stopped 304stopping condition 281storage 195 see also memorystorage device 6storage media 5store 195store address 195store location 195stored program concept 377storyboard 241streaming audio 38, 57–58streaming video 38strike-through 27string data 331string operator 288strongly typed languages 286structure diagram 252structure errors 301structured planning technique 243structured programming 243Structured Query Language (SQL) 102

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Structured Systems Analysis and Design Methodology (SSADM) 231style 32stylesheet 32–33, 322stylus 39, 40, 190subdirectory 12, 68subdomain 114subfolder 12submenu 65subprogram 278–279, 280–281subroutine 280 open/closed subroutine 281subroutine library 280subroutine symbol 294subschema 94subscript 27, 326subscripted variable 328subtask 241supercomputer 186supernode 125superscript 27supervisor program 363support personnel 159surfing 115suspended 304sustain 54swipe card 167, 191switched hub 142symbol table 362symbolic addressing 268symbols ECMA symbols 291 flowchart symbols 252, 253, 291–294 logic symbol 395 program flowchart symbols 291–292 system flowchart symbols 250–251symmetric digital subscriber line (SDSL) 111synchronous transmission 384syndication 120syntax 284syntax analysis 360syntax error 301synthesiser 59 music synthesiser 58–59 speech synthesiser 179system characteristics 244system crash 305system cycle 228system development cycle 230system diagram 249system flowchart 249–251system life cycle 228–229system software 8–9, 355systems analysis 232systems analyst 157Systems Application Architecture (SAA) 365systems design 232systems designer 157systems development personnel 157–158systems documentation 234systems engineer 157systems implementation 233Systems Network Architecture (SNA) 365systems program 356systems programmer 157systems specification 243systems support personnel 159systems testing 233

tab stop 29, 30table array as 327 for data presentation 30, 31 in databases 94 decision table 291, 292 file allocation table 202 hash table 342 look-up table 266 name table 362 pivot table 88–89 symbol table 362 trace table 301, 302 truth table 394table of contents 24tablet graphics tablet 39, 40 tablet PC 185, 186tabs 29–30tag (HTML) 319, 320–321tag (information) 78, 79TCP (Transmission Control Protocol) 388TCP/IP (Transmission Control Protocol/Internet Protocol) 141, 387

TDM (time division multiplexor) 221technical documentation 234technical support staff 159tele-processing 16telecommunications 3teleconferencing 126telemetry 147teleworking 126template 33–34temporary (temp) file 344terabytes 12terminal 139terminal adapter 220terminal node 326terminal services server 138terminator 271test case 299test data 299test plan 299testing 298–300 acceptance testing 241 alpha testing 240 beta testing 240–241 developmental testing 240–241 systems testing 233tethering 112TEX 23text box 66text editor 20text manipulation 20–34text search 23texture 36thermal printer 213thermal wax printer 216thesaurus 24thin client 138–139third normal form (3NF) 98–99, 101third-generation computer 184third-generation language (3GL) 309thrashing 371thread 127, 363tight 28timbre 51, 52time division multiplexor (TDM) 221time slice 221, 363

time-sharing 16timer 374timing information 79Timsort 348title case 27toggle 67token 134token ring network 134, 136toolbar 67toolbox 67tools 67 authoring tool 316 debugging tool 300 productivity tool 6 visual programming tools 244top-down programming 243top-level domain 114touch-sensitive device 190touch-sensitive keyboard 190touchscreen 190tower 185TP (twisted pair) 222trace 300trace table 301, 302track 196, 197trackball 190trackerball 190trackpad 190trackpoint 190tractor feed 217trailer 389training 159transaction 77transaction file 344transaction processing 16transducer 223translator 358transmission 384–386Transmission Control Protocol (TCP) 388Transmission Control Protocol/ Internet Protocol (TCP/IP) 141, 387

transparency 71transputer 368trapdoor functions 170trapdoor Trojan 172tree 325–326Trojan 172Trojan horse 172TRUE 103truncation 351truncation error 351trusted service provider 164trusted third party 164truth table 394truth value 103, 288Turing test 152–153turnaround document 81turnkey system 240turtle 317turtle graphics 317tutorial 6, 73tweening 44twisted pair (TP) 222two-address instruction 268two-dimensional array 327two’s complement 336type see data typetype check 75typeface 25

UCE (unsolicited commercial e-mail) 128ULA (uncommitted logic array) 382

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UML (Unified Modelling Language) 254–258unary operator 288uncommitted logic array (ULA) 382unconditional 276underflow 350underline 27undocumented feature 244Unicode 324, 433Unified Modelling Language (UML) 254–258Uniform Resource Identifier (URI) 113–114Uniform Resource Locator (URL) 113uninstall 19units 423–425UNIVAC I 184Universal Product Code (UPC) 78UNIX 357unprotected software 173unset 265unshielded twisted pair (UTP) 222unsolicited commercial email (UCE) 128UPC (Universal Product Code) 78update 303, 344upgrade, software 242upload 350upper case 26upright 27upward compatibility 239URI (Uniform Resource Identifier) 113–114URL (Uniform Resource Locator) 113USB stick 200use case diagram 255user documentation 71user environment 63user friendly 71user identification (user ID) 167user interface 63user support personnel 159user transparent 71user-defined data type 331username 167utility program 358UTP (unshielded twisted pair) 222

V.22bis 388V.32bis 388V.34 388vaccine utility 171validation 75–76Value Added Network Service (VANS) 140VANS (Value Added Network Service) 140variable 286 dummy variable 287 dynamic variable 286 global variable 286 local variable 286 static variable 286 subscripted variable 328variable check 300variable type 331variable-length record 329VDU (visual display unit) 210vector 370vector graphics 38–39, 212vectoring 377

Venn diagram 395–396verification 76–77 disk verification 198 request verification 203version 242version management 239very large-scale integration (VLSI) 381very small aperture terminal (VSAT) 392video, streaming 38video adapter 211video adapter card 211video camera, digital 44video capture card 45video card 211video clip 331video data 331video digitiser 45video editing system 46–48video RAM (VRAM) 211video-conferencing 126view 94virtual learning environment (VLE) 177virtual local area network (VLAN) 143virtual machine 360virtual memory 371virtual network 136virtual private network 136virtual private networking (VPN) 136virtual reality 147virtual reality cave 148virtual reality systems 144–145virtualisation 138–139virus 171virus checking 171visual display unit (VDU) 210visual programming tools 244VLAN (virtual local area network) 143VLE (virtual learning environment) 177Voice over Internet Protocol (VOIP) 125voice synthesiser 179VoIP (Voice over Internet Protocol) 125volatile memory 194, 196volume 50von Neumann architecture 377Vonage 125VPN (virtual private networking) 136VRAM (video RAM) 211VSAT (very small aperture terminal) 392

W3C (World Wide Web Consortium) 115wait state 376walkthrough 300WAN (wide area network) 132warm start 306waterfall model 229waveform 50wavelength 50, 51Web 2.0 117web, the 115web editor 22web log 120

web page 115web server 138webcam 117webmail 123webmaster 117website 115–117website developer 158weight 25what you see is what you get (WYSIWYG) 18while loop 275white balance 38white box 299white space 28Wi-Fi 143wide area network (WAN) 132widow 31–32wildcard 68WiMAX 112WIMP (Windows Icons Menus Pointers) environment 63window (screen) 63–64Windows (operating system) 357Windows Icons Menus Pointers (WIMP) environment 63wire connector 221–222wire frame 36wireless access point 142wireless communication 221wireless Ethernet 143wireless mesh 143wizard 71word 12–13 reserved word 289 status word 265word length 12–13word processor (computer) 187word processor (software) 20–21word wrap 29workspace 14–15workstation 140 music workstation 61World Wide Web Consortium (W3C) 115World Wide Web (WWW) 115worm 171WORM (write-once, read-many) 200write 344write protection 202–203write-once, read-many (WORM) 200WYSIWYG (what you see is what you get) 18

X.25 388X.400 388xD card 44XDCAM 45XML 319, 322XNOR (Exclusive-NOR) gate 400–401XOR (Exclusive-OR) gate 400XOR operation 266XY plotter 217

YMCK 207YouTube 127

ZIP files 349zipping 349ZMODEM 388

450