Microsoft 0
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`Microsoft"
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`NVIDIA 1009
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`PUBLISHED BY
`Microsoft Press
`A Division of Microsoft Corporation
`One Microsoft Way
`Redmond, Washington 98052-6399
`
`Copyright © 2002 by 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 Computer Dictionary.--5th ed.
`p. cm.
`ISBN 0-7356-1495-4
`1. Computers--Dictionaries. 2. Microcomputers--Dictionaries.
`
`AQ76.5. M52267 2002
`004' .03--dc2 l
`
`200219714
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`Printed and bound in the United States of America.
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`2 3 4 5 6 7 8 9 QWT
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`7 6 5 4 3 2
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`Distributed in Canada by H.B. Fenn and Company Ltd.
`
`A CIP catalogue record for this book is available from the British Library.
`
`Microsoft Press books are available through booksellers and distributors worldwide. For further informa(cid:173)
`tion about international editions, contact your local Microsoft Corporation office or contact Microsoft
`Press International directly at fax (425) 936-7329. Visit our Web site at www.microsoft.com/mspress.
`Send comments to mspinput@microsojt.com.
`
`Active Desktop, Active Directory, ActiveMovie, ActiveStore, ActiveSync, ActiveX, Authcnticode,
`BackOffice, BizTalk, ClearType, Direct3D, DirectAnimation, DirectDraw, Directlnput, DirectMusic,
`DirectPlay, DirectShow, DirectSound, DirectX, Entourage, FoxPro, FrontPage, Hotmail, IntelliEye,
`IntelliMouse, IntelliSense, JScript, MapPoint, Microsoft, Microsoft Press, Mobile Explorer, MS-DOS,
`MSN, Music Central, Neu\1eeting, Outlook, PhotoDraw, PowerPoint, SharePoint, UltimateTV, Visio,
`Visual Basic, Visual C++, Visual FoxPro, Visual InterDev, Visual J++, Visual SourceSafe, Visual Studio,
`Win32, Win32s, Windows, Windows Media, Windows NT, Xbox are either registered trademarks or
`trademarks of Microsoft Corporation in the United States and/or other countries. Other product and
`company names mentioned herein may be the trademarks of their respective owners.
`
`The example companies, organizations, products, domain names, e-mail addresses, logos, people, places,
`and events depicted herein are fictitious. No association with any real company, organization, product,
`domain name, e-mail address, logo, person, place, or event is intended or should be infeITed.
`
`Acquisitions Editor: Alex Blanton
`Project Editor: Sandra Haynes
`
`Body Part No. XOS-41929
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`2
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`

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`meltdown
`
`memory rnanagernent
`
`the virus also changes the registry, infects the Normal.clot
`Word template (which, in turn, infects new documents),
`and, in Office 2000, disables the Word macro virus warning.
`Although the Melissa virus does not dcslTOY data, it can
`affect e-mail performance through the increased volume of
`messages. If an infected document is open at a time when
`the day of the month is the same as the minute value of the
`current time, the virus inserts the text "Twenty-two points,
`plus triple-word-score, plus fifty points for using all my let(cid:173)
`ters. Game's over. I'm outta here" at the current location of
`the cursor. The virus was named after an acquaintance of
`the hacker who developed it.
`meltdown n. 1. The complete collapse of a computer net(cid:173)
`work caused by a higher level of traffic than the network can
`support. The term refers, by analogy, to the accidental melt(cid:173)
`ing down of a nuclear reactor core. 2. Colloquially, the
`brealcdown of a person, usually in a job situation, caused by
`overwork, stress, or failure.
`member n. l. In object-oriented programming, a variable
`or routine that is part of a class. See also C++, class. 2. A
`value that is part of a set data structure. See also set2 (defi(cid:173)
`nition 1 ).
`membrane keyboard n. A keyboard in which an unbro(cid:173)
`ken plastic or rubber shell (a membrane) covers keys that
`have little or no travel (movement). Rather than use nor(cid:173)
`mal, full-travel keys, membrane keyboards use pressure(cid:173)
`sensitive areas that are sometimes, but not always, defined
`by small bumps under the membrane.
`memo field n. A field in a database file that can contain
`unstructured text.
`memo pad n. A note-taking feature offered by many per(cid:173)
`sonal digital assistants and other hm1dheld computing
`devices. Memo pad allows for the entry of short notes via
`typing or handwriting recognition applications. The notes
`can be categorized, organized, and edited later.
`
`memory n. A device where infornrntion can be stored and
`retrieved. In the most general sense, memory can refer to
`external storage such as disk drives or tape drives; in com(cid:173)
`mon usage, it refers only to a computer's main memory,
`the fast semiconductor storage (RAM) directly connected
`to the processor. See also core, EEPROM, EPROM, flash
`memory, PROM, RAM, ROM. Compare bubble memory,
`mass storage.
`
`i
`j
`I
`l l
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`j
`i
`J
`'
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`memory bank n. The physical location on a motherboard
`where a memory module can be inserted. See also bank
`(definition 1 ).
`memory board 11. A plug-in printed circuit board that con(cid:173)
`tains one or more memory chips. See also memory chip.
`
`memory cache n. See CPU cache.
`memory card n. A memory module that is used to extend
`RAM storage capacity or in place of a hard disk in a porta(cid:173)
`ble computer, such as a laptop, notebook, or handheld PC.
`The module is usually the size of a credit card and can be
`plugged into a PCMCIA-compliant portable computer.
`The module can be composed of EPROM, RAM, or ROM
`chips or flash memory. Also called: RAM card, ROM
`card. See also EPROM, flash memory, handheld PC, hard
`disk, memory cartridge, module (definition 2), PCMCIA,
`RAM, ROM.
`memory cartridge n. A plug-in module containing RAM
`(random access memory) chips that can be used to store
`data or programs. Memory cart1idges arc used primarily in
`portable computers as smaller, lighter (but more expen(cid:173)
`sive) substitutes for disk drives. Memory cartridges typi(cid:173)
`cally use either a nonvolatile form of RAM, which does
`not lose its contents when power is turned off, or battery(cid:173)
`backecl RAM, which maintains its contents by drawing
`current from a rechargeable battery within the cartridge.
`Also called: RAM cartridge. See also memory card,
`RAM. Compare ROM cartridge.
`memory cell 11. An electronic circuit that stores one bit of
`data. See also bit.
`memory chip n. An integrated circuit devoted to memory
`storage. The memory storage can be volatile and hold data
`temporarily, such as RAM, or nonvolatile and hold data
`permanently, such as ROM, EPROM, EEPROM, or
`PROM. See also EEPROM, EPROM, integrated circuit,
`memory board, nonvolatile memory, PROM, RAM, vola(cid:173)
`tile memory.
`memory management n. l. In operating systems for
`personal computers, procedures for optimizing the use of
`RAM (random access memory). These procedures include
`selectively storing data, monitoring it carefully, and free(cid:173)
`ing memory when the data is no longer needed. Most cur(cid:173)
`rent operating systems optimize RAM usage on their own;
`some older operating systems, such as early versions of
`MS-DOS, required the use of third-party utilities to opti(cid:173)
`mize RAM usage and necessitated that the user be more
`
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`I
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`111emo1y management program
`
`menu item
`
`knowledgeable about how the operating system and appli(cid:173)
`cations used memory. See also memory management unit,
`RAM. 2. In programming, the process of ensuring that a
`program releases each chunk of memory when it is no
`longer needed. In some languages, such as C and C++, the
`programmer must keep track of memory usage by the pro(cid:173)
`gram. Java, a newer language, automatically frees any
`chunk of memory that is not in use. See also C, C++, gar(cid:173)
`bage collection, Java.
`
`memory management program n. 1. A program used to
`store data and programs in system memory, monitor their
`use, and reassign the freed space following their execu(cid:173)
`tion. 2. A program that uses hard disk space as an exten(cid:173)
`sion of the random access memory (RAM).
`
`memory management unit n. The hardware that sup(cid:173)
`ports the mapping of virtual memory addresses to physical
`memory addresses. In some systems, such as those based
`on the 68020, the memory management unit is separate
`from the processor. In most modern microcomputers,
`however, the memory management unit is built into the
`CPU chip. In some systems, the memory management unit
`provides interfacing between the microprocessor and
`memory. This type of memory management unit is typi(cid:173)
`cally responsible for address multiplexing and, in the case
`of DRAMs, the refresh cycle. Acronym: MMU. See also
`physical address, refresh cycle, virtual address.
`
`memory model n. The approach used to address the code
`and the data that are used in a computer program. The
`memory model dictates how much memory can be used in
`a program for code and how much for data. Most comput(cid:173)
`ers with a flat address space support only a single memory
`model. Computers with a segmented address space usually
`support multiple memory models. See also compact
`model, flat address space, large model, medium model,
`segmented address space, small model, tiny model.
`
`memory module 17. A removable circuit board, cartridge,
`or other caiTier that contains one or more RAM memory
`chips. See also memory card, memory cartridge, RAM.
`
`memory-resident adj. Permanently located in a com(cid:173)
`puter's memory, rather than swapped in and out of mem(cid:173)
`ory as needed. See also memory, TSR.
`
`memory scrubbing 11. 1. In mainframe computers, the
`process of a computer reading its own memory during idle
`periods in order to find and fix enors. 2. The process of
`
`examining and correcting enors as data is transferred from
`memory to the CPU of a computer.
`
`memory size 17. The memory capacity of a computer, usu(cid:173)
`ally measured in megabytes. See also meg~byte, memory.
`
`memory typewriter n. An electric typewriter with inter(cid:173)
`nal memory and typically a one-line liquid crystal display
`for viewing lhe contents of that memory. Memory type(cid:173)
`writers can usually hold one page of text at a time, to
`which small modifications can be made. Memory type(cid:173)
`writers usually do not retain the contents of memory when
`power is turned off.
`
`MEMS n. Acronym for micro-electromechanical systems.
`A technology combining computers with extremely tiny
`mechanical devices. MEMS devices contain microcir(cid:173)
`cuitry on a tiny silicon chip onto which a mechanical
`device such as a sensor or an actuator is attached. MEMS
`devices ai·e used in switches, pacemakers, games, GPS
`tracking, data storage, and for accelerometers in air bags.
`Because MEMS devices have the potential to be manufac(cid:173)
`tured in large quantities for little cost, many additional
`MEMS products are being planned or studied.
`
`menu n. A list of options from which a user can make a
`selection in order to perform a desired action, such as
`choosing a command or applying a paiticular format to
`part of a document. Many application programs, espe(cid:173)
`cially those that offer a graphical interface, use menus as a
`means of providing the user with an easily learned, easy(cid:173)
`to-use alternative to memorizing program commands and
`their appropriate usage.
`
`menu bar 11. A rectangular bar displayed in an application
`program's on-screen window, often at the top, from which
`menus can be selected by the user. Names of available
`menus are displayed in the menu bar; choosing one with
`the keyboai·d or with a mouse causes the list of options in
`that menu to be displayed.
`
`menu-driven adj. Using menus to present choices of
`commands and available options. Menu-driven programs
`are usually considered foencllier and easier to learn than
`programs with a command-line interface. Compare com(cid:173)
`mand-line interface.
`
`menu item n. A choice on a menu, selectable by either
`the keyboard or a mouse. In some instances, a menu item
`that is not available (that is, not appropriate) for a given
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`noise
`
`noise n. 1. Any inte1ierence that affects the operation of a
`device. 2. Unwanted electrical signals, produced either
`naturally or by the circuitry, that distort or degrade the
`quality or performance of a communications channel. See
`also distortion.
`nonbreaking space n. A character that replaces the
`standard space character in order to keep two words
`together on one line rather than allowing a line to break
`between them.
`noncompetes n. An agreement between employer and
`employee that states that the employee will not accept
`work with a competing company for a specified length of
`time after leaving the employer's company. Noncompete
`agreements are common in high-tech companies and are
`typically requested to help maintain company secrets and
`retain valuable employees.
`
`nonconductor n. See insulator.
`noncontiguous data structure n. In programming, a
`data structure whose elements are not stored contiguously
`in memory. Data structures such as graphs and trees, whose
`elements are connected by pointers, are noncontiguous data
`structures. Compare contiguous data structure.
`
`nondedicated server 11. A computer on a network that
`can function as both a client and a server; typically, a
`desktop machine on a peer-to-peer network. Compare
`dedicated server.
`nondestructive readout n. A reading operation that
`does not destroy the data read, either because the storage
`technology is capable of retaining the data or because the
`reading operation is accompanied by a data refresh
`(update) function. Acronym: NDR, NDRO. Compare
`destructive read.
`nonexecutable statement n. 1. A program statement
`that cannot be executed because it lies outside the flow of
`execution through the program. For example, a statement
`immediately following a return() statement but before the
`end of the block in C is nonexecutable. 2. A type defini(cid:173)
`tion, variable declaration, preprocessor command, com(cid:173)
`ment, or other statement in a program that is not translated
`into executable machine code.
`nonimpact printer n. Any printer that makes marks on
`the paper without striking it mechanically. The most com(cid:173)
`mon types are ink-jet, thennal, and laser printers. See also
`ink-jet printer, laser printer, the1mal printer. Compare
`impact printer.
`
`NO-OP
`
`noninterlaced adj. Pertaining to a display method on ras(cid:173)
`ter-scan monitors in which the electron beam scans each
`line of the screen once dming each refresh cycle. Compare
`interlaced.
`nonmaskable interrupt 11. A hardware interrupt that
`bypasses and takes priority over inteITupt requests gener(cid:173)
`ated by software and by the keyboard and other such
`devices. A nonmaskable interrupt cannot be overruled
`(masked) by another service request and is issued to the
`microprocessor only in disastrous circumstances, such as
`severe memory errors or impending power failures. Acro(cid:173)
`nym: NMI. Compare maskable interrupt.
`nonprocedural language n. A programming language
`that does not follow the procedural paradigm of executing
`statements, subroutine calls, and control structures
`sequentially but instead describes a set of facts and rela(cid:173)
`tionships and then is queried for specific results. Compare
`procedural language.
`nonreturn to zero n. 1. In data transmission, a method of
`encoding data in which the signal representing binary dig(cid:173)
`its alternates between positive and negative voltage when
`there is a change in digits from 1 to 0 or vice versa. In
`other words, the signal does not return to a zero, or neu(cid:173)
`tral, level after transmission of each bit. Timing is used to
`distinguish one bit from the next. 2. In the recording of
`data on a magnetic surface, a method in which one mag(cid:173)
`netic state represenls a 1 and, usually, the opposite state
`represents a 0. Acronym: NRZ.
`nontrivial adj. Being either difficult or particularly mean(cid:173)
`ingful. For example, a complicated programmed proce··
`dure to handle a difficult problem would represent a
`nontrivial solution.
`Non-Uniform Memory Access n. See NUMA.
`nonuniform memory architecture 11. A system archi(cid:173)
`tecture designed for Sequent's Non-Uniform Access
`Memory, a type of distributed shared memory using a
`number of shared memory segments instead of a single
`centralized physical memory. Acronym: NUMA.
`
`nonvolatile memory n. A storage system that does not
`lose data when power is removed from it. Intended to refer
`to core memory, ROM, EPROM, flash memory, bubble
`memory, or battery-backed CMOS RAM, the term is occa(cid:173)
`sionally used in reference to disk subsystems as well. See
`also bubble memory, CMOS RAM, core, EPROM, flash
`memory, ROM.
`NO-OP n. See no-operation instruction.
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`volatile memory
`
`V series
`
`volatile memory n. 1. Memory, such as RAM, that loses
`its data when the power is shut off. Compare nonvolatile
`memory. 2. Memo1y used by a program that can change
`independently of the program, such as memory shared by
`another program or by an interrupt service routine.
`
`volt n. The unit used to measure potential difference or
`electromotive force. One volt is defined as the potential
`across which 1 coulomb of charge will do 1 joule of work,
`or the potential generated by 1 ampere of current flowing
`through 1 ohm of resistance. See also electromotive force.
`
`voltage n. See electromotive force.
`
`voltage regulator 11. A circuit or circuit component that
`maintains a constant output voltage despite variations in
`input voltage.
`
`volts alternating current n. The measure of the peak-to(cid:173)
`peak voltage swing of an elect1ical signal. Acronym: VAC.
`
`volume n. 1. A disk or tape that stores computer data.
`Sometimes, large hard disks are divided into several vol(cid:173)
`umes, each of which is treated as a separate disk. 2. The
`loudness of an audio signal.
`
`volume label n. A name for a disk or tape. MS-DOS sys(cid:173)
`tems, which seldom use disk names except in directory
`listings, use the term volume label. Apple Macintosh sys(cid:173)
`tems, which often refer lo disks by name, use the term vol(cid:173)
`ume name.
`
`volume name 11. See volume label.
`
`volume reference number n. See volume serial number.
`
`volume serial number n. The optional identifying vol(cid:173)
`ume number of a disk or tape. MS-DOS systems use the
`term volume serial number. Apple Macintosh systems use
`the term volume reference number. A volume serial num(cid:173)
`ber is not the same as a volume label or volume name.
`Compare volume label.
`
`VON n. Acronym for voice on the net. A broad category of
`hardware and software technology for real-time voice and
`video transmission over the Internet. The term was coined
`by Jeff Pulver, who formed a group called the VON Coali(cid:173)
`tion, which opposes regulation of VON technology and
`promotes VON to the public.
`
`von Neumann architecture 11. The most common struc(cid:173)
`ture for computer systems, attributed to the mathematician
`John von Neumann. It uses the concept of a program that
`can be permanently stored in a computer and manipulated
`or made self-modifying through machine-based instruc(cid:173)
`tions. Sequential processing is characteristic of von Neu-
`
`mann architecture. Parallel architectures have evolved to
`improve on the encumbrances of sequential instructions.
`See also parallel computer.
`
`von Neumann bottleneck n. Competition between data
`and instmctions for CPU time. Mathematician John von
`Neumann was the first to show that a computer based on
`architecture linking a single processor with memory will
`actually spend more time retrieving data from memory
`than processing it. The bottleneck arises when the proces(cid:173)
`sor has to trade off between executing a large number of
`instructions per second and reading in a large amount of
`data in the same time. See also CPU.
`
`VPD n. Acronym for virtual printer device driver. See vir(cid:173)
`tual device driver.
`
`VPN n. See virtual private network.
`
`VR n. See virtual reality.
`
`VRAM n. See video RAM.
`
`VRC 11. Acronym for vertical redundancy check. A
`method for checking the accuracy of transmitted data.
`VRC generates an extra bit (parity bit) for each character
`transmitted. The parity bit indicates whether the character
`contains an odd or an even number of 1 bits. If its value
`does not match the type of the character, that character is
`assumed to be incorrectly transmitted. See also parity.
`Compare LRC.
`
`VRML 11. Acronym for Virtual Reality Modeling Lan(cid:173)
`guage. A scene desc1iption language for creating 3-D inter(cid:173)
`active Web graphics similar to those found in some video
`games, allowing the user to "move around" within a graphic
`image and interact with objects. VRML, a subset of Silicon
`Graphics' Inventor File Format (ASCII), was created by
`Mark Pesce and Tony Pmisi in 1994. VRML files can be
`created in a text editor, although CAD packages, modeling
`and animation packages, and VRNIL authoring software are
`the tools prefcITed by most VRML authors. VRML files
`reside on an HTTP server; links to these files can be embed(cid:173)
`ded in HTML documents, or users can access the VRML
`files directly. To view VRML Web pages, users need a
`VRML-enabled browser or a VRML plug-in for Internet
`Explorer or Netscape Navigator. See also 3-D graphic,
`HTML document, HTTP server (definition 1).
`
`v-root 11. See virtual root.
`
`V series n. The series of ITU-T (formerly CCITT) rec(cid:173)
`ommendations relating to modems and modem communi(cid:173)
`cations over the public phone system, including signaling,
`coding, and circuit characteristics. See the table.
`
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