MICROSOFT PRESS
`
`SECOND EDITION
`
`COMPLETELY
`
`REVISED AND
`UPDATED, WITH NEW
`DEFINITIONS AND
`ILLUSTRATIONS
`
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`
`The Comprehensive
`
`Standard for
`Business, School,
`Library, and Home
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`Microsoft
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`MICROSOFT PRESS®
`
`Computer
`Dictionary
`
`SECOND
`
`EDITION
`
`•Yl
`
`Microsoft
`PRESS
`
`

`
`PUBLISHED BY
`Microsoft Press
`A Division of Microsoft Corporation
`One Microsoft Way
`Redmond, Washington 98052-6399
`
`Copyright © 1994 by Microsoft Press
`All rights reserved. No part ofthecontents ofthis book may bereproduced or
`transmitted in any form orby any means without the written permission ofthe publisher.
`Library of Congress Cataloging-in-Publication Data
`
`Microsoft Press computer dictionary : the comprehensive standard for
`business, school, library, and home / Microsoft Press. -- 2nd ed.
`p.
`cm.
`ISBN 1-55615-597-2
`1. Computers--Dictionaries. 2. Microcomputers- -Dictionaries.
`I. Microsoft Press.
`11. Title: Computerdictionary.
`QA76.15.M54
`1993
`004'.03--dc20
`
`93-29868
`
`CIP
`
`Printed and bound in the United States of America.
`
`5 6 7 8 9 MLML 9 8 7 6 5
`
`Distributed to the book trade in Canada byMacmillan of Canada, a division ofCanada
`Publishing Corporation.
`Distributed tothebook trade outside the United States and Canada by
`Penguin Books Ltd.
`
`Penguin Books Ltd., Harmondsworth, Middlesex, England
`Penguin Books Australia Ltd., Ringwood, Victoria, Australia
`Penguin Books N.Z. Ltd., 182-190 Wairau Road, Auckland 10, NewZealand
`
`British Cataloging-in-Publication Data available.
`
`Project Editor: Casey D. Doyle
`Manuscript Editor: Alice Copp Smith
`Technical Editors: Mary Dejong,JeffCarey, Dail Magee,Jr.,Jim Fuchs, Seth McEvoy
`
`

`
`destructive read
`
`device driver
`
`software. This type of program enables the user
`to lay out text and graphics on the screen and see
`what the results will be; for refining parts of the
`document, these programs often include word-
`processing and graphics features in addition to
`layout capabilities. As a final step, the finished
`document is printed either on a laser printer or,
`for the best quality, bytypesetting equipment,
`destructive read Sometimes abbreviated DRO
`(destructive readout). An attribute of certain
`memory systems, notably core systems. In a de
`structive read of a memory location, the data is
`passed on to the processor, but the copy m
`memory is destroyed by the process ofreading.
`Destructive memory systems require special logic
`to rewrite data back toa memory location after it
`is read.
`detail file See transaction file.
`detection Discovery ofacertain condition that a^
`fects acomputer system orthe data with which it
`works. Some detection methods are based on
`routine functions; for example, a microprocessor
`detects signals (interrupts) that indicate that a
`program or device requires attention. Other de
`tection methods aredesigned to uncover Haws or
`errors in operation; for example, error detection
`in communications uses sampling, calculation,
`and comparison to determine whether informa
`tion is received in the same form in which it was
`transmitted.
`determinant In database design theory, any at
`tribute orcombination ofattributes on which any
`other attribute or combination of attributes is
`functionally dependent. For example, if a data
`base contains address information, the combina
`tion of the attributes ADDRESS + CITY +STATE
`determines the value for ZIPCODE. That is, any
`given address (as fully defined by ADDRESS,
`CITY, and STATE) can have one and only one
`ZIPCODE. ZIPCODE is functionally dependent on
`ADDRESS +CITY +STATE. Likewise, ina collec
`tion ofinfonnation about employees, the attribute
`SOCIAL-SECURITY-NUMBER is most likely adeter
`minant of LASTNAME. LASTNAME is functionally
`dependent onSOCIAL-SECURITY-NUMBER,
`determinism In computing, the ability to predict
`
`anoutcome ortoknow inadvance how data will
`be manipulated by a processing system. Adeter
`ministic simulation, for example, isone inwhich
`a certain inputalways produces the same output;
`a deterministic algorithm is one whose function
`ality is always the same.
`developer's toolkit Aset ofroutines (usually in
`oneor more libraries) designed to allow develop
`ers to more easily write programs for a given
`computer, operating system, or user interface.
`See also library, toolbox.
`device Ageneric term for a computer subsystem.
`Printers, serial ports, and disk drives are often re
`ferred to as devices; such subsystems frequently
`require their own controlling software, called de
`vice drivers. Seealso device driver.
`device address A location within the address
`space of a computer's random access memory
`(RAM) thatcanbealtered either by themicropro
`cessor orby an external device. Device addresses
`are different from other locations in RAM, which
`can bealtered only by the microprocessor. To the
`microprocessor, the incoming information ap
`pears as data stored at alocation in RAM. To the
`device, the location appears simply as a register
`to which it can send data or from which it can
`read data put there by the microprocessor. See
`«/50device, input/output, RAM.
`device control character See control character,
`device dependence The requirement that a par
`ticular device be present or available for the use
`ofa program, interface, or protocol. Device de
`pendence in a program is often considered un
`fortunate because the program either is limited
`to one system or requires adjustments for every
`other type of system on which it is to run. Com
`pare device independence.
`devicedriver Asoftware component thatpermits
`a computer system to communicate with a de
`vice. Aprinter driver is a device driver that trans
`lates computer data into a form understood by
`the intended printer. In most cases, the driver
`also manipulates the hardware in order to trans
`mit the data to the device. However, device driv
`ers
`associated with
`application
`packages
`typically perform only the data translation; these