The HUTCHINSON
`
`DICTIONARY OF
`
`COMPUTING
`MULTIMEDIA
`
`AND THE
`
`INTERNET
`
`THIRD EDITION
`
`Dropbox 1 123
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`A H
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`elicon
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`Dropbox 1123
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`Text and original illustrations © Helicon Publishing Ltd 1997, 1998, 1999
`First Published 1997
`
`Second Edition 1998
`
`Third Edition 1999
`
`Reprinted 1999
`
`All rights reserved
`
`Helicon Publishing Ltd
`
`42 Hythe Bridge Street
`Oxford 0X1 2EP
`
`e-mail: admin@heiicon.co.uk
`
`Web Site: httpzfs’wwwheliconcouk
`
`ISBN 1-85986—287-X
`
`British Cataloguing in Publication Data
`
`A catalogue record for this book is available from the British Library
`
`Terms which are known to be trademarks or service marks have been
`
`appropriately capitalized.
`
`The use of a term in this book should not be regarded as affecting the validity or
`
`legal status of any proprietary rights which may be claimed in that trademark or
`service mark.
`
`Printed and bound in Great Britain by
`The Bath Press Ltd, Bath, Somerset
`
`Acknowledgements
`
`We would like to thank the following for screen shots of proprietory
`
`software: Adobe (Illustrator), MegaTech Software GmbH (MegaCAD),
`
`Microsoft Corp. (Excel, Internet Explorer. PowerPoint,Word),
`
`Netscape (Navigator); and the following WWW pages:
`AltaVista (http:/fwwwaltavista.digiiialeomf),
`Infoseek (http:!fguide-p.infoseekcomf),
`Snap (http://wwwsnapcom/j,
`Lycos (http://www. lycoscomf),
`Pepsi (httpszwwwpepsicomf).
`Jennicarn (http:f/www.jennicam.coml),
`
`Yahoo (http:/lwww.yahoo.com/).
`
`
`
`

`

`This material may be protected by Copyright law (Title 17 U.S. Code)
`
`

`

`
`
`desktop relational database. easy to learn and includes
`programming capabilities
`
`74 DATA BUS
`
`Filemaker Pro FileMaker
`
`
`
`Oracle
`
`
`
`Oracle
`Software
`
`database
`
`The features of some major
`database programs.
`
`
`
`Manufacturer Description
` Access
`
`desktop relational database which features wizards and
`Microsoft
`
`
`
`
`Approach
`Lotus
`
`
`
`macros; included in Microsoft Office Professional for ‘r‘v‘indpws
`
`
`versatile and easy-to-use desktop relational database
`software tor Windows or Mac
`
`
`
`high-level professional relational database management
`
`system for Windows, D03. or UNIX
`
`
`
`
`powerful, scalable relational database management system
`that includes point-andeolick GUI tools that speed and Simplify
`
`database management
`
`
`
`
`
`powerful, scalable relational database management system
`designed specifically for distributed clientrserver computing
`
`There are three main types (or‘models’) of database: hierarchical, network,
`and relational, of which relational is the most widely used. In a relational
`
`database data are viewed as a collection of linked tables. Afree-text databasg
`is one that holds the unstructured text of articles or books in a form that permits
`rapid searching.
`
`A collection of databases is known as a databank. A database-management
`
`system (DBMS) program ensures that the integrity of the data is maintained by
`controlling the degree of access of the #applications programs using the data.
`Databases are normally used by large organizations with mainframes or
`
`minicomputers.
`
`A telephone directory stored as a database might allow all the people whose
`names start with the letter B to be selected by one program, and all those living
`in Chicago by another.
`
`Databases are usually created using a database program that enables a user
`to define the database structure by selecting the number of fields, naming those
`fields, and allocating the type and amount of data that is valid for each field. To
`
`sort records within a database, one or more sortfields may be selected, so that
`when the data is sorted, it is ordered according to the contents of these fields. A
`kqfiem is used to give a unique identifier to a particular record. Data programs
`also determine how data can be viewed on screen or extracted into files.
`
`_
`
` data bus the electrical pathway, or 4bus, used to carry data between the
`
`components of the computer.
`
`data capture collecting information for computer processing and analysis.
`Examples of automated. data capture include using a Qsensor that
`
`continuously monitors physical conditions such as temperature, or scanning bar
`__
`codes to produce detailed receipts at a shop check—out (‘9point-of-sale terminal).
`Manual data capture methods include reading electricity meters, or filling in a I
`form or questionnaire.
`
`
`
`

`

`
`
`REFRESH 233
`
`ray-tracing in computer graphics, method of rendering sharp, detailed images.
`
`Designers specify the size, shape, colour, and texture of objects and the type and
`
`location of light sources, and use a program to devise a mathematical model
`
`tracing how light rays would bounce off the surfaces. The results, complete with
`
`shading, shadows, and reflections, depict ‘virtual worlds’ with near—photographic
`
`clarity.
`
`RBOC abbreviation for Regional Bell Operating Company, formed with the
`
`US government break-up of America's giant telecommunications operator, AT&T.
`
`Since AT&T was known as Ma Bell, the RBOCs are sometimes known as Baby
`Bells.
`
`FIDP abbreviation for DRemote Desktop Protocol.
`
`read-onlyr storage a permanent means of storing data so that it can be read any
`
`number of times but cannot be modified. (ID-ROM is a read-only storage medium;
`CD-ROMs come with the data already encoded on them.
`'
`
`RealAudio software system for broadcasting sound over the Internet in real
`
`time. Broadcasters use an encoder and a special server to provide content, and
`members of the ‘audience‘ can listen to live radio or create a customized news
`
`broadcast which they can download whenever they wish. RealAudio Software is
`
`supplied by RealNetworks Inc (formerly called Progressive Networks). Its
`
`RealPlayer software plays ReaLAudio and RealVideo.
`
`real-time system a program that responds to events in the world as they
`
`happen. For example, an automatic-pilot program in an aircraft must respond
`
`instantly in order to correct deviations from its course. Process control, robotics,
`
`games, and many military applications are examples of real-time systems.
`
`record collection of related data items orfields. A record usually forms part of a
`
`Eelite. Records may be of eitherfixed or variable length; variable records
`
`require a separator at the end of the field, in order that the end of the record can
`
`be detected by the computer.
`
`recursion technique whereby a function or fiprocedure calls itself into use in
`
`order to enable a complex problem to be broken down into simpler steps. For
`
`example, a function that finds the factorial of a number n (calculates the product
`of all the whole numbers between 1 and n) would obtain its result by multiplying
`
`n by the factorial of n - l.
`
`redundancy duplication of information. Redundancy is often used as a check,
`when an additional check digit or bit is included. See also Ovalidation.
`
`refresh to redraw the image on a D‘VDU. All such images are a series of frames
`
`created by a device — in the case of a cathode ray tube, an electron beam — which
`‘paints’ the image on the screen, isipbtel by pixel. This process is too rapid for
`the human eye to detect, although a high refresh rate (number of times a
`
`screen is redrawn per second) is said to reduce eye strain.
`
`
`' REALAUDIO
`HeaiAudio Players are
`distributed free, and are
`also available as
`
`
`
`
`
`
`
`Netscape and Internet
`Explorer piug-ins. The
`FlealAudio Web site is
`httdewwxaalaudiocom.
`
`
`
`
`
`