MECR.OSOFT PRESSG)
`
`I”
`
`
`
`THE COMPREHENSIVE
`
`STANDARD FOR
`
`BUSINESS, SCHOOL,
`
`LIBRARY, AND HOME
`
`Microsoft
`
`Apple Inc.
`APL1118
`
`US. Patent No. 8,724,622
`
`001
`
`Apple Inc.
`APL1118
`U.S. Patent No. 8,724,622
`
`

`

`PUBLISHED BY
`Microsoft Press
`A Dwision of Microsoft Corporation
`One Microsoft Way
`Redmond. Washington 98052-6399
`Copyright © 1991 by Microsoft Press. a division of Microsoft Corporation.
`All rights reserved. No part of the contents of this book may
`be reproduced or transmitted In any form or by any means without
`the written permission of the publisher.
`Library of Congress Cataloging-in—Publication Data
`Microsoft Press computer dictionary : the comprehensive standard for
`business, school, library, and home.
`13.
`(:11.
`ISBN 165615-2314]
`I. Computers-Dictionaries.
`1. NHth Press.
`QA?6.15.M54
`1991
`004.16'_03——dc20
`
`2. Mcrocomputers—Dictionaries.
`
`91-9904
`(21?
`
`Printed and bound in the United States of America.
`
`5 6 7 s 9 MIMI.
`
`6 5 4 3 2
`
`Distributed to the book trade in Canada by Macmillan of Canada. a division
`of Canada Publishing Corporation.
`Distributed to the book 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 NZ. Ltd“ 182—190 Wairau Road, Auckland 10, New Zealand
`British Cataloging-in-Pubiication Data available.
`
`Acquisitions Editor: Marjorie Schlaikjer
`-
`Project Editor: Mary Ann Jones
`“Ilechnical Editors: Dmrid Rygn'ryr, Jeff Hinsch, Mar}.r Dejong. Dai] Magee. Jr.
`Manuscript Editor: Pameia Bear-on
`Copy Editor: Alice Oopp Smith
`
`002
`
`002
`
`

`

`INTRODUCTION
`
`The Microsofi Press Computer Dictionary is designed to be a comprehensive and
`authoritative source of definitions for computer—related terms and acronyms. Writ-
`ten and reviewed by a distinguished team of experts from the computer industry
`and the business and academic communities, the dictionary includes terms drawn
`from a wide variety of disciplines:
`
`Applications
`Communications
`Data and Data Storage
`Databases
`Desktop Publishing
`Electronics
`
`Hardware
`' Chips, Cards, and Boards
`Computers
`Disks, Drives, and Other Media
`Keyboards
`Printers and Plotters
`Video
`Other Devices
`
`History
`Information Processing
`General Computing
`Input/Output
`Memory and Memory Management
`Networks
`
`Output
`Print
`Screen
`Programming
`Systems and Environments
`
`Although the book covers nearly every aspect of computing, it does not in-
`clude entries on specific companies or on specific makes and models of com~
`puters, nor does it contain entries on mom application software products, although
`some key products of universal importance are covered.
`
`Order of Presentation
`
`Entries are alphabetized letter by letter. Spaces are ignored, as are characters such
`as hyphens and slashes; for example, Baudot code falls between baud and baud
`rate, and mcbine-mdependem falls between machine identification and
`machine instruction. Numbers and symbols are located at the beginning of the
`book and are listed in ascending ASCII order. If an entry begins with a letter or let-
`ters but contains a number, it is listed alphabetically, according to the initial let-
`terfs), and then according to ASCII order. Thus, V20 precedes V2.76, and both
`precede VAB.
`
`003
`
`003
`
`

`

`Format
`
`Information in each entry is presented in a consistent format: entry name, abbre—
`viation, pronunciation (if supplied), alternative name or names, definition, and
`cross-references (if any).
`Phonetic pronunciations are given where appropriate or in cases where pro—
`nunciation might not be apparent. If an acronym is pronounced simply by saying
`the successive letters it contains, no pronunciation is given.
`Cross-references are of three kinds: A See reference simply points to another
`entry that contains the information sought; a See also reference points to one or
`more entries that contain additional or supplemental information about the topic;
`and a Compare reference points to an entry or entries that offer contrast.
`Illustrations are called out in the text. In most cases, illustrations appear on the
`same page as the entries to which they apply. In some instances, however, page-
`layout requirements have forced them to a subsequent page. In any event, the cap—
`tion of each illustration identifies the entry to which it belongs.
`
`Future Printings and Editions
`
`Every effort has been made to ensure the accuracy and completeness of this book.
`If you find an error, think that an entry does not contain enough information, 0r
`seek an entry that does not appear in this edition, please let us know. Address your
`letter to: Microsoft Press, One Microsoft Way, Redmond, WA 98052, Attention.-
`Dicn'onary Editor:
`
`viii
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`

`
`
`phone line and initiate a call by transmitting a
`stored telephone number as a series of pulses or
`[01155.
`
`AUTOEXECBAT A special—purpose batch file (set
`of commands) that is automatically can'ied out by
`the MS—DOS operating system whenever the com-
`puter is started or restarted. AUTOEICECBAT is
`created by the user or, in later versions of MS-DOS,
`by the operating system when the system is in-
`stalled. The file contains basic startup commands
`that help configure (tailor) the system to installed
`devices and to the preferences of the user.
`auto-key See typematic.
`antenatal theory The study of computing pro-
`cesses, their capabilities. and their limitations—-the
`manner in which systems receive input, process it,
`and produce output; also, the study of the relation—
`ship between behavioral theories and the opera-
`tion and use of automated devices. See also cellular
`automata.
`
`automated ofi'ioe A rather vague term used to refer
`to an office in which work is performed with the
`aid of computers,
`telecommunications facilities,
`and other electronic devices.
`automatic answering See auto answer.
`automatic data processing See data processing.
`automatic dialing See auto dial.
`automatic error correction A process that, upon
`detection ofan internal processing error or a data-
`transmission error, invokes and provides informa—
`tion to an appropriate routine designed to correct
`the error or retry the operation.
`Automatic Sequence Controlled Calculator See
`Mark I.
`automonjmr A process or system feature capable
`of continually assessing the status of its own inter—
`nal environment.
`
`equipment. programs, activities, and procedures to
`determine how efficiently the entire system is per—
`forming, especially in terms of ensuring the in-
`tegrity and security of data.
`audit trail in relation to computers, a means of
`tracing all activities affecting a piece of information
`such as a data record from the time it enters the
`system to the time it leaves. An audit trail docu-
`ments the path from input to output and should
`provide enough information to reconstruct or
`verify the entire sequence, either manually or
`through automated tracking procedures. For ex-
`ample. when several people are working on a
`document in a networked environment, an audit
`trail makes it possible to know who made a par-
`ticular change and when, or even to see the docu—
`ment before and after that person's changes.
`authoring language A computer language or ap—
`plication development system designed primarily
`for creating programs, databases, and materials for
`computer-aided instruction (CAI). The best-known
`example in the microcomputer world is PILOT, de—
`veloped originally at the University of California,
`San Francisco, which is a language used to create
`lessons.
`authoring system A combination of hardware and
`software designed to ease the tasks involved in
`producing interactive programs. Seeaiso authoring
`language, interactive program.
`authorization In relation to computers. especially
`'[0 remote computers on a network open to more
`than one person, the right granted to an individual
`to use the system and the data stored on it. Authori-
`zation is typically set up by a system administrator
`and checked and cleared by the computer, which
`requires that the user provide some type of iden-
`tification, such as a code number or a password,
`that the machine can verify against
`its internal
`records. The terms permission and privilege are
`synonymous with authorization See also network,
`system administrator.
`authorization code Set? password.
`auto me:- The ability of a modem to answer in-
`coming telephone calls automatically. See also
`answer mode.
`
`autopolling Also called polling. The process of pe-
`riodically determining the status of each device in
`a set so that the active program can process events
`generated through each device. The process is
`used to determine the status of a range of events,
`such as whether a key or a mouse button was
`pressed or whether new data is available at a serial
`port. Autopolling can be compared with event-
`driven processing, in which a low-level routine in
`auto dial The ability of a modem to open a tele-
`
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`F‘
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`the operating system alerts a program or routine to
`an event occurring in a device with an interrupt or
`a message. rather than requiring the program to
`check each device in turn.
`auto-repeat See typernatic.
`amorestart A process or system feature that can
`automatically restart the system after certain types
`of errors or power supply failures.
`autosave A program feature that automatically
`Saves an open file to disk or to another medium at
`preset intervals or after a certain number of key-
`strokes. Autosave is a means of ensuring that
`changes to a document are periodically saved.
`autostart routine A process by which a system or
`device is automatically prepared for operation
`upon the occurrence of some predetermined event
`such as power-up. See also AUTOEXECBAT, auto-
`restart, bootstrap.
`autocrace A feature of many drawing programs
`that draws lines along the edges of a him-tapped im-
`age in order to convert the image into an object—
`oriented one. See also bit—mapped graphios, object-
`oriented graphios.
`A/U'X A version of the multiuserI multitasking UNIX
`operating system, provided by Apple Computer for
`the Macintosh II and based on the AT&T System V,
`release 2 of UNIX. AIUX incorporates a number of
`Apple features; among them is support for the Mac-
`intosh Toolbox so that applications running under
`
`A/UX can provide users with the graphics—based
`interface characteristic of that computer. 599 also
`System V.
`AUX Logical device name for auxiliary device; a
`name reserved by the MS—DOS operating system
`for the standard auxiliary device. AUX usually
`refers to a system’s first serial portI which is also
`known as COM].
`auxiliary equipment See accessory.
`auxiliary storage Any storage medium. such as
`disk or tape,
`that is not directly accessed by a
`computer's microprocessor, as is random access
`memory. More modern usage tends to refer to such
`media simply as storage or permanent storage and
`to the RAM chips that the microprocessor uses di-
`rectly for temporary storage as memory.
`availability In processing,
`the accessibility of a
`computer system or a resource in terms of usage (as
`in "availability of a network printer") or as a per-
`centage of die total amount of time the device is
`needed.
`availablethne See uptime.
`axis In a chart or other two-dimensional system
`using coordinates, either the horizontal line (x—axis)
`or the vertical line (yaxis) that serves as a refer—
`ence against which values are plotted. A third line
`(the z—axis) is used in a three~dimensional coordi—
`nate system to represent depth. See also Cartesian
`coordinates.
`
`
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`27
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`polarized component
`
`tive, but by convention current is considered to
`flow from pmitive to negative. The term polarity is
`also used to refer to the orientation of north and
`south magnetic poles.
`polarized component A circuit component that
`must be installed with its leads in a particular
`orientation with respect to the polarity of the cir—
`cuit. Diodes, rectifiers, and some capacitors are
`examples of polarized components. Examples
`of nonpolarized components are resistors. most
`capacitors, and inductors.
`polarizing filter A transparent piece of glass or
`plastic, usually dark gray or brown. that polarizes
`the light passing through it—Lhat is, it allows only
`waves vibrating in a certain direction to pass
`through. Polarizing filters are often used to reduce
`glare on monitor screens. See also glare filter.
`Polish notation See prefix notation.
`polling See autopolling.
`polling cycle The time and sequence required for
`a program to poll each of its devices or network
`nodes. See also autopolling.
`polygon Any two-dimensional closed shape with
`multiple sides. such as a hexagon, an octagon. or a
`triangle. Computer users encounter polygons—or
`tools for creating polygons—in graphics programs
`such as MacPaint and Windows Paint. Graphical
`interfaces can include polygons as geometric
`primitiveswobjects that programs can create and
`manipulate as discrete entities.
`polyline In computer graphics. a line consisting of
`multiple connected segments. The lines connect—
`ing the stars in a representation of the handle ofthe
`Big Dipper, for example, would be a polyline. Poly-
`lines are used in CAD and other graphics pro—
`grams. Graphical interfaces can include polylines
`as geometric primitiveswobjects that programs
`can create and manipulate as discrete entities.
`polymorphism In an object-oriented program-
`ming language, the ability to redefine a routine in a
`derived class (a class that inherited its data struc—
`tures and routines from another class). Polymor-
`phism allows the programmer to define a base
`class that includes routines that perform standard
`operations on groups of related objects, without
`regard to the exact type of each object. The pro—
`
`grammer can redefine the routines. taking into ac-
`count the type of the object, in the derived classes
`for each of the types. See also class, derived class,
`object.
`pop To fetch the top (most recently added) element
`of a stack, removing that element from the stack in
`the process. A stack is a data structure generally
`used to temporarily hold pieces of data being trans-
`ferred or the partial result of an arithmetic opera—
`tion. Comte push; see also stack.
`populate To fill the sockets of a circuit board. See
`also fully populated board.
`port In computer hardware. a location for passing
`data in and out of a computing device. Micropro~
`cessors have ports for sending and receiving data
`bits; these ports are usually dedicated locations in
`memory. Full computer systems have ports for con—
`necting peripheral devices such as printers and
`modems. See also input/output port.
`In programming, to change a program in order
`to run it on a different computer; more loosely. to
`move documents, graphics, and other files from
`one computer to another.
`' portability With reference to computer programs,
`the ability of a program to run on or be changed to
`run on more than one computer system or under
`more than one operating system. Highly portable
`software can he moved to other systems with little
`effort; moderately portable software can be moved
`only with substantial effort; and nonportable soft—
`ware can be moved only with effort similar to or
`greater than the effort of writing the original pro-
`gram. See also port, portable.
`portable An adjective describing a program that is
`capable of being moved to various systems. Wth
`reference to computers. portable commonly refers
`to a computer that can be moved or carried with
`ease. See also portable computer.
`portable computer Any computer designed to be
`moved easily. Portable computers can be charac—
`terized by size and weight. as shown in the table on
`the following page.
`portable language A language that runs on various
`systems and that can be used for developing soft-
`ware for various systems. C. FORTRAN. and Ada
`are portable languages because their implementa-
`
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