MICROSOFT PRESS*
`
`aI
`
`‘THE COMPREHENSIVE
`
`STANDARD FOR
`
`U.S. Patent No. 8,724,622
`
`BUSINESS, SCHOOL,
`LIBRARY, AND HOME
`
`heted
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`AppleInc.
`APL1118
`
`001
`
`Apple Inc.
`APL1118
`U.S. Patent No. 8,724,622
`
`

`

`PUBLISHED BY
`Microsoft Press
`A Division 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 computerdictionary : the comprehensive standard for
`business, school, library, and home.
`p.
`cm.
`ISBN 1-55615-231-0
`1. Computers--Dictionaries.
`I. Microsoft Press.
`QA76.15.M54_
`1991
`004.16'03--de20
`
`2. Microcomputers--Dictionaries,
`
`91-9904
`CIP
`
`Printed and bound in the United States of America.
`
`56789 MLML 65432
`
`Distributed to the booktrade 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 BooksLtd.
`
`Penguin Books Ltd., Harmondsworth, Middlesex, England
`Penguin Books Australia Ltd., Ringwood, Victoria, Australia
`Penguin BooksN.Z.Ltd., 182-190 Wairau Road, Auckland 10, New Zealand
`British Cataloging-in-Publication Data available.
`
`Acquisitions Editor: Marjorie Schlaikjer
`“
`Project Editor: Mary Ann Jones
`Technical Editors: David Rygmyr, Jeff Hinsch, Mary DeJong, Dail Magee,Jr.
`Manuscript Editor: Pamela Beason
`Copy Editor: Alice Copp Smith
`
`002
`
`002
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`

`

`INTRODUCTION
`
`The Microsoft 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 notin-
`clude entries on specific companies or on specific makes and models of com-
`puters, nor doesit contain entries on most 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 hyphensandslashes, for example, Baudot code falls between baud and baud
`rate, and machine-independent
`falls between machine identification and
`machine instruction. Numbers and symbols are located at the beginning of the
`book andare listed in ascending ASCII order. If an entry begins withaletterorlet-
`ters but contains a number,it is listed alphabetically, according to the initial let-
`ter(s), and then according to ASCII order. Thus, V20 precedes V.2x, 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-referencesare 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 mostcases,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 eachillustration identifies the entry to which it belongs.
`
`Future Printings and Editions
`Every effort has been madeto ensure the accuracy and completeness of this book.
`If you find an error, think that an entry does not contain enough information, or
`seek an entry that does not appearin this edition, please let us know. Address your
`letter to: Microsoft Press, One Microsoft Way, Redmond, WA 98052, Attention:
`Dictionary Editor.
`
`viii
`
`004
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`
`
`phone line andinitiate a call by transmitting a
`stored telephone numberas a series of pulses or
`tones.
`
`AUTOEXEC.BAT A special-purpose batchfile (set
`of commands)that is automatically carried out by
`the MS-DOS operating system whenever the com-
`puter is started or restarted. AUTOEXEC.BATis
`created by the useror,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.
`automata theory The study of computing pro-
`cesses, their capabilities, and their limitations—the
`mannerin 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 office 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 of an 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
`MarkI.
`automonitor 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-
`mentbefore andafter 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. See also authoring
`language, interactive program.
`authorization In relation to computers, especially
`to remote computers on a network open to more
`than one person, the right granted to an individual
`to use the system andthedata stored onit. 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 See password.
`auto answer The ability of a modem to answerin-
`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-
`
`auto dial The ability of a modem to openatele- driven processing, in which a low-level routine in
`
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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 devicein turn.
`auto-repeat See typematic.
`autorestart A process or system feature that can
`automatically restart the system after certain types
`of errors or powersupply failures.
`autosave A program feature that automatically
`saves an openfile to disk or to another medium at
`preset intervals or after a certain numberof key-
`strokes. Autosave is a means of ensuring that
`changes to a documentare 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 AUTOEXEC.BAT,auto-
`restart, bootstrap.
`autotrace A feature of many drawing programs
`that drawslines along the edges ofa bitmapped im-
`age in order to convert the image into an object-
`oriented one. See also bit-mapped graphics, object-
`oriented graphics.
`A/UX Aversion of the multiuser, multitasking UNIX
`operating system, provided by Apple Computer for
`the Macintosh II and based on the AT&T System V,
`release 2 of UNIX. A/UX incorporates a number of
`Apple features; among them is supportfor the Mac-
`intosh Toolbox so that applications running under
`
`A/UX can provide users with the graphics-based
`interface characteristic of that computer. See 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'sfirst serial port, which is also
`known as COMI.
`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 usagetendsto 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 resourcein terms of usage (as
`in “availability of a network printer”) or as a per-
`centage of the total amount of time the device is
`needed.
`available time See uptime.
`axis In a chart or other two-dimensional system
`using coordinates, either the horizontal line (x-axis)
`or the vertical line (axis) 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.
`
`
`
`27
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`

`polarized component
`
`grammer can redefine the routines, taking into ac-
`tive, but by convention current is considered to
`countthe type of the object, in the derived classes
`flow from positive to negative. The term polarity is
`also used to refer to the orientation of north and
`for each of the types. See also class, derived class,
`object.
`south magnetic poles.
`pop Tofetch the top (most recently added) element
`polarized componentA circuit component that
`of a stack, removing that element from the stack in
`must be installed with its leads in a particular
`the process. A stack is a data structure generally
`orientation with respect to the polarity of the cir-
`used to temporarily hold pieces of data being trans-
`cuit. Diodes, rectifiers, and some capacitors are
`examples of polarized components. Examples
`ferred or the partial result of an arithmetic opera-
`tion. Compare push;see also stack.
`of nonpolarized components are resistors, most
`populate Tofill the sockets of a circuit board. See
`capacitors, and inductors.
`also fully populated board.
`polarizing filter A transparent piece of glass or
`port In computer hardware, a location for passing
`plastic, usually dark gray or brown,that polarizes
`data in and out of a computing device. Micropro-
`the light passing through it—thatis, it allows only
`cessors have ports for sending and receiving data
`waves vibrating in a certain direction to pass
`through. Polarizing filters are often used to reduce
`bits; these ports are usually dedicated locations in
`memory. Full computer systems have portsfor con-
`glare on monitor screens. See also glare filter.
`necting peripheral devices such as printers and
`Polish notation See prefix notation.
`modems. See also input/output port.
`polling See autopolling.
`In programming, to change a program in order
`polling cycle The time and sequence required for
`a program to poll each ofits devices or network
`to run it on a different computer; more loosely, to
`move documents, graphics, and otherfiles from
`nodes. See also autopolling.
`one computerto another.
`polygon Any two-dimensional closed shape with
`multiple sides, such as a hexagon, an octagon, or a
`* portability With reference to computer programs,
`the ability of a program to run on or be changed to
`triangle. Computer users encounter polygons—or
`run on more than one computer system or under
`tools for creating polygons—in graphics programs
`such as MacPaint and Windows Paint. Graphical
`more than one operating system. Highly portable
`software can be moved to other systems with little
`interfaces can include polygons as geometric
`primitives—objects that programs can create and
`effort; moderately portable software can be moved
`only with substantial effort; and nonportable soft-
`manipulate as discrete entities.
`ware can be moved only with effort similar to or
`polyline In computer graphics, a line consisting of
`multiple connected segments. The lines connect-
`greater than the effort of writing the original pro-
`ing the stars in a representation ofthe handle of the
`gram. See also port, portable.
`portable An adjective describing a program thatis
`Big Dipper, for example, would beapolyline. Poly-
`lines are used in CAD and other graphics pro-
`capable of being moved to various systems. With
`grams. Graphical interfaces can include polylines
`reference to computers, portable commonly refers
`as geometric primitives—objects that programs
`to a computer that can be moved orcarried with
`can create and manipulate asdiscrete entities.
`ease. See also portable computer.
`polymorphism In an object-oriented program-
`portable computer Any computer designed to be
`ming language,the ability to redefine a routine in a
`moved easily. Portable computers can be charac-
`derived class (a class that inherited its data struc-
`terized by size and weight, as shown in the table on
`tures and routines from another class). Polymor-
`the following page.
`phism allows the programmer to define a base
`portable language A language that runs on various
`class that includes routines that perform standard
`systems and that can be used for developing soft-
`operations on groups of related objects, without
`ware for various systems. C, FORTRAN, and Ada
`regard to the exact type of each object. The pro-
`are portable languages because their implementa-
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