The most comprehensive computer reference available! More than
`10,000 definitions and explanations, including 5,000 new or revised
`terms. Covers every topic imaginable-from laptop to mainframe,
`microchip to the World Wide Web. Ideal for beginners, power users,
`or computer professionals.
`
`Wii5n m] QG1®~il 1:f~~~ ~1jU~~[BiOt~13
`\iVt~~UBOO m[;Um~D ~~~~HIiJ~Y
`
`The
`om u er
`
`.'
`
`I a
`
`.Alan Freedman
`
`Author of the Leading
`Dictionary of Computer Tem~s:
`THE COMPUTER GLOSSARY.
`
`HP-ACC-00976197
`
`

`
`This book is available at a special discount wben
`ordered in bulk quantities. For information,
`contact Special Sales Department, AMACOM,
`an imprint of AMA Publications, a division of
`Ame:rican Management Association,
`1601 Broadway, New York, NY 10019.
`
`This publication is designed to provide acCurate and authoritative
`information in regard to the subject matter covered. It is sold with the
`understanding that the publisher is not engaged j n tendering legal,
`accounting, or other professional service. Iflegal advice or other
`expert assistance is required, the services of a competent professional
`person should.be sought.
`
`. Library of Congress CatalogIng-In-PublicatIon Data
`
`Freedman, Alan
`Computer desktop encyclopedia
`cm ..
`p.
`ISBN 0-8144-7985-5
`1. Computers--D1ctlonarles.
`QA76.15.~732 1999
`004'.03~-dc21
`
`I Alan Freed_an. -- 2nd ed.
`
`1. Title.
`
`98-32408
`CIP
`
`© 1999 The Computer Language Company Inc.
`Point Pleasant, PA 18950, USA.
`All rights reserved.
`Printed in the United States of America.
`
`The publication may not be reptoduced,
`stored in a retrieval system,
`or transmitted in whole Ot in part,
`in any form or by an means, dectronic,
`mechanical, photocopying, recording, or othewise,
`. without the prior written permission of AMACOM,
`an imprint of AMA Publications, a division of
`American Management Association,
`1601 Broadway, New York, NY 10019.
`
`Printing number
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`10
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`9
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`8
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`7
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`6
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`HP-ACC-00976198
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`-
`
`background ink
`
`In order to distinguish any image on sc:re<:n, whether text or graphics,
`(2) The base:. or backdrop color.
`there must be a contrasting background color.
`background ink
`A highly reflective OCR ink used to print the parts of the for~ nor recognized by a scanner.
`background noise
`An extraneous signal that has crept into a line. channel or circuit.
`background processing
`Processing in which the program is not visibly interacting with the user. Most personal computers use
`operating systems that run background tasks only when foreground tasks are idle, such as between
`keystro~. Advanced. multitasking operating systems let badcgTOund programs be given any priority fram
`low to high.
`backing storage
`Same as auxiliary itoragt.
`backlit
`An LCD screen that has its own light source from the back of the screen, making the background
`.
`brighter and characters appear sharper.
`BackOfflce
`A suite of netWork server software products from Microsoft mat includes Windows NT Server. SQL
`Server, Systems Management Server (SMS), SNA Server and Mail Server.
`·backplane
`An interconnecting device iliat mayor may IIOt have imclligence, but typicaJly has sockets that cards
`(boards) plug into. Although resistors may be used, II passive backpLme adds no pro=sing in the circuir:
`An intelligent baekpLme, or active backplane. may.have microprocessor or controUer-driven circuitry that
`adds a little or a lot of processing. See bus.
`backside cache
`A memory cache thar has a dedicated channel to the CPU, enabling it run at the full speed of the
`CPU. See inlint racht and lookaridt ClUhe.
`backslash
`The backslash symbol (\) is used as a sep~tor between folder an~ file names in DOS, Windows and
`OS/2 when me full pam to a file is written out. For example. the path c:\cdelcde.ae points to the
`CDE.EXE. file in the CDE folder on the C: drive.
`.
`When the universal naming convention (UNe) is used, double backslash (\\) characters serve as a
`prefix to the server name (see UNC).
`
`Just the Worst!
`11ie bllcksl~ chomw:r was thewocst symbol that could ever have been chosen for dlls purpose. Nor
`only is d,e back81asb key nor loom:d in a st:l1ldard place on the kcyb<J'ild. but-lmerner addresses use
`forward dashes since they come from UNIX. ThJ: itony is thar the DOS' path synm. was copkd from
`UNIX, but somebody must havc fclt compelled to show originality of auilionhip and dlUS reversed the
`separator symbols. N"ow both methods are io our faces day after day. See posh.
`backsolver
`See.oilln'.
`backspace
`(I) To move the screen cursor one column to the left, deleting the character that was in that position.
`A backspace to the printer moves the prinr head one column to the left.
`(2) To move to the previous block on a magnetic tape.
`back up
`To make a copy of important data onto a different storage medium for safety.
`
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`Binder
`
`a
`
`(2) 1n a communications network, to esrablish a software connection berween one protocol and
`another. Data flows from the application [0 the transport protocol to the network protocol to the dara
`link protocol and. then OntO the network. Binding the protocols creates the internal pathway.
`(3) (BIND) (Berkeley Internet Name Domain) A public domain DNS server that is available for mosr
`venions of UNIX.
`
`Binder
`A Microsoft Office workbook file that lets users combine related documenrs from different Office
`applications. The documents can be viewed, saved, opcned, e-mailed and printed as a group. The Binder
`is an ActiveX Documents container, and Office applications. such as Ex.cel and Word, are ActiveX
`Documents servers. The documents are known as ktiveX Doeumenu objectS, which were formedy
`known as DocObjects. See ArhlltX DocummtJ.
`
`bindery ,
`A NetWare file used for security and accounting in NetWare 2.x and 3.x. A bindery pertains only ro
`the server it resides in and contains the names and passwords of users and groups of users authorized to log
`in to that server. It also holds information about other services provided by the server to the client (print,
`modem, garo:wuy, etc.).
`'
`NDS (NetWare Directory Service) is the bindery counterpart in NetWare 4.x, but NOS is global
`oriented, lllllJUges multiple servers and provides a naming service, wwch the bindery does not. Bindery
`emulation software csuhles NetWarc 2.x and 3.:1 clients to access service.! on NerWare 4.x servers. See
`NDS.
`
`bindings .
`A set of linkages or assignments. See bind.
`binding time
`(1) In program compilation, the point in time when symbolic references to data ate converted into
`physical machine addresses.
`(2) In prhgrammlng languages, when a variable is assigned its type (integer, string. etc.). Traditional
`compilers :uu:I ....emblers provide carll' binding and assign rypes at compilation. Object-oriented
`languages provide l:tte binding and assign types at runtime wh~ the variable 'receives a value from the
`keyboard or other source.
`BlnHex
`A" utility and encoding format that originated on the Macintosh which is used to convert binary files
`into 7·bit ASCII for communications over Internet e-mail. Files formatted in BinHex use the .HQX
`extension. See MIME, UU,oding and Wi"",tk.
`biochlp
`See gmt ,hip.
`biomechanics
`The study of the anatomical principles of movement. Biomechanical applications on the computer
`employ stick modeling to analyze the movement of athletes as well as racing horses.
`biometrics
`Means' biological measurements and refers to eyes, voice. hand and fingerprints. which are used' for
`authentication. See authmti,atiIJn.
`
`bionic
`,
`A machine thar is patterned after principles found in' humans or nature; for example, robots. It also
`refers to artificial devices implanted into humans replacing or extending normal h~an functions.
`BIOS
`(Basic Input OutpUt System) Although BlOSs were cceated more than 40 years ago as routines for
`handling input and output, the term generally refe~ to the PC's system BIOS, which is stored on a chip
`and provides an interface between the operating system and the peripheral hardware. The BIOS supporrs
`all peripheral technologies and internal services such as the realtime clock (time and date).
`On startup, the BIOS tests the system and prepares the computer for operation by querying the
`
`74
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`computer Desktop Encyclopedia
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`BISON
`
`Controllers
`on motherboard
`
`CMOS configuration settings and searching
`for other BIOSs on the plug-in boards and
`setting up pointers (inrerrupt vectors) in
`memory to access those rounnes. It then loads
`the operadng system and passes concrol to it.
`The BIOS accepts requests from the drivers as
`well as the application ptograms.
`BlOSs must periodically be updated to
`keep pace with new peripheral technologies. If
`the BIOS is stored on a ROM chip (ROM
`BIOS), it must be replaced. Newer BrOSs are
`scored on a flil$h memory chip that can be
`upgraded via software. See CMOS setup.
`biosensor
`A device that detects and analyzes body
`movement, tcmperatwe or fluids and turns it
`into an electronic signal. It may be worn
`(heapgear, bracelet, etc.) or wed in a handheld
`or Stationary unit. See data gjqve.
`BIOS setup
`Same as CMOS setup.
`bIpolar
`A category of high-speed microelectronic circuit design, which was used to create the flrst transistor
`and the first integrated circuit. The most common variety of bipolar chip is TTL (rransistor transistor
`logic), Emirter coupled logic (ECL) and integnlted injeclion logic (I2t) nre also part of the bipolar family.
`Today, bipolar rnd CMOS arc the two .major trrnsistor tochnologles. Most all personal computers use
`CMOS, and even large l11ainfr:unes chat nave traditionally used bipolar have given way to CMOS designs.
`CMOS uses far less energy chan bipolar.
`However, bipolar rransistors are still widely used for high radio frequency (RF) applications that reach
`imo the gigahem range, which CMOS eechnology cannoe bwdJe,
`The bipolar transisror works by pulsing a line c.alIed the baS(, which allows current to flow from the
`emht., to rhe coll.elor, or vice ~ersa depending on the: des;gn.
`.
`
`BIOS Interaction
`On startup, the BIOS searches all peripheral controllers
`in the system to obtain the current configuration, which
`it makes available to the software.
`
`bipolar transmIssion
`A diglt2l transmission eechnique rb3t alternates between positive and negative signals. The Is and Os
`are determined by varying amplieudes ar both polarities while non-dara is zero amplitude.
`
`BIPS
`(Billion Instructions Per Second) See MIPS.
`biqUinary code
`Meaning two-five code. A system for storing decimal digits in a four-bit binary number. The
`biquinary code was used in the abacus. See ablUUS.
`
`birefringence
`Using a crystal co split light into twO frequencies rhat crave! at different speed.s and at right angles to
`each other. It's used co filter out a color in an LCD display.
`bls
`Second version. It means twice in Old Latin, or encore in French. Ter means three. For example,
`Y.27bis an,d Y.27ter are the second and third versions of the Y.27 standard.
`BISON
`(Broadband ISDN) A second-generation ISDN scandan! thar USe.l fiber optic cables for speeds of 155
`Mbps and higher. BISDN's bottom three layers oHmplcmcntlltioll comprise ATM (asynchronous transfer
`mode), which by itself is gaining ground as a nerworking teeho.ology for LANs and WANs.
`
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`
`body type
`
`block move
`The ability to mark a contiguous segment of toct or data and move it.
`
`block multiplexor channel
`A high-speed mode of opention within IBM's parallel channel. See parallel channel.
`blow
`To write code Or data into a PROM chip by blowing the fuses of the 0 bits. The 1 bits are left alone.
`blow up
`Same as crash, bomb or abmd.
`
`blue laser
`A type oflaser capable of wriring bits with up t~ five times greater density than the infrared lasers
`In 1993, IBM demonstrated a recording density of2.S billion bits per square inch on 0.
`commonly used.
`magneto.optic disk. It is expected that blue lasers will be commercially used in a few yeats.
`
`blue screen
`See cofer kty.
`
`Blue Screen of Death
`AWind~ws NT err~r that causes the computer to lock up, and the screen turns blue. The solution is
`to reboot, See BlrIck Screm ofDeath.
`
`BMP file
`(Bit MaP file) Also known l!S a "bump' file, it Is a Window> and OS/2 bianapped graphics file
`format,' It is the Windows native bitmap format, and every Wmdows appliClrioll lias access to the BMP
`software rourines in Windows that suppOrt it. BMP files provide formats for 2, IG, 256 or 16 miUion
`colors (l·bit, 4-bit, 8-bit and 24-bit color). BMP files we the .BMP or .DIB extC1lsions (DID stand.! ror
`Device.Independent Bitmap).
`
`BHC connector
`(British Naval Connector) A commonly used plug and socket for audio, video and networking
`applications. BNes connect two-wite coaxial cable (signal and ground) using a bayonet moUnt. After the
`plug is inserted, the bayon.lte mechanism causes the pins to be pinched into the locking groove when the
`plug is tluned.. See RC1 connecror ror i1Jusrntion.
`BNF
`See Backus-Naur firm,
`
`board
`See card. prinUd circuit board and BBS.
`
`board level
`Electronic components that arc mounted on a printed circuit board instead of in .. cabi"net or finished
`housing.
`
`boardware
`Same as board level.
`
`BOC
`(Dell Operating Company) One of22 telephone companies that was formerly part ofAT&:r and now
`part of one of the $cven regional Bell telephone companies.
`
`body text
`The base ·ront used ror text in a paragraph. In m~y desktop publishing programs. any paragraph that
`is not tagged separately is assigned the body tat style.
`
`body type
`The typeface 0.09, size commonly used for text in paragraph copy. Typically 10 points.
`
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`degausser
`
`DECsystem
`(1) A series of RISe-based, 32-bit computelli from Digital that run under ULTRIX. Introduced in
`1989, the 5400 mode! is a Q-bus system; the 5800 model uses the XMI bus.
`(2) A series of mainframes from Digital that were introduced from 1974 through 1980 and wm the
`successor to the 36-bit PDP-lO computers.
`
`DECtaik
`A voice synthesizing system from Digital that accepts serial ASCII r~ and converts it into audible
`speech. It is used in Touch-tone telephone response systems as well as for voice-output ror visually
`handicapped users.
`DeCwindows
`Digital's windowing architecture, based on X Window, Velliion 11. It is compatible with X Window
`while adding a variety of enhancements.
`
`dedicated channel
`A computer channel or communications line that is used for one purpose.
`dedicated line
`A phone or other communications line used for one purpose. Synonymous with uaud line and private
`line.
`.
`
`dedicated service
`A service that is not shared by other usrrs or organizations.
`de facto standard
`A widely-used format or language not endorsed by a standards organization.
`default
`The current setting or action taken by hardware or software if rhe user has not specified otherwise.
`
`default directory
`Same as currmt directory.
`
`default drive
`The disk drive used if no other drive is specified.
`
`default font
`. The typeface and type size used if none other is specified.
`
`default gateway
`.
`The router used to forward all traffic that is not addressed to II. station within the local subnet.
`default proflle
`The normal de&u1r settings assigned to an application or system. See usn- JifttUItprofik.
`
`defragger
`Also called an optimizer program, it is a software utility that defragments a disk. It rewrites ,the files
`and stores them in :adjacent seCtors. Sophisticated defraggers allow frequently-used files to be placed at the
`front of the disk for faster retrieval.
`
`defragment
`To reorganize rhe disk by putting fues into contiguous order.
`.Because the operating S}'ftem stOres new
`data in whatever frec space is available. Qata files become spread out across the di.!k if they are updared
`often. This causes clttn read/write head movement to read them baek. Periodically, the hard cli.k should
`be defragmented to put files back into order. See deftaggtr.
`
`degausser
`A device that removes unwanred magnetism from a moniror or the read/write head in a disk or t2pe
`drive. A monitor may have a built·in degaUS5ing function with a degau.ss button on the fronr control
`panel. See gaurs.
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`....
`
`eSulte
`
`eSuite
`A Java-based suite of applications from Locus that includes word processing. spreadsheet, e-mail and
`pre.lentauon graphics. It runs in any NC or PC that has a Java Virtual Machin.e. FOrnlerly code named
`Kona, the individual executable programs are considerably smaller thnn counterpart applications in
`Microsoft Office and other Windows-based software.
`
`e-talllng
`(Electronic-reTAILING) An online storefront. See ~kt:tro1Jic commtru.
`
`EtherLoop
`(ETHERnet Local LOOP) A transmission technology from Norte! that uses Ethernet packets at up to
`10 Mbps Ova sl>lJldard reL!phone lines between the customer and teleo central office (CO). It does not
`usc the rcgubr Ethernet CSMNCD collision method. EtherLoop is a last mile technology that is said to
`eliminate much of the crosstalk 3,S.\Ocillted with DSL. See /tlst mile.
`
`Ethernet
`The most widely-used LAN access method, which is defined by the IEEE 802.3 standard (Token Ring
`is the next most popular). Ethernet is normally a shared media LAN. AU srations on the segment sMre
`the total· bandwidth, which is either 10 Mbps (Ethernet), 100 Mbps (Fast Ethernet) or 1000 Mbps
`(Gigabit Ethernet). With switched Ethernet, each sender and receiver pair ·have the full bandwidth.
`Standard Ethernet (1OBaseS), also called Thick Erh~mtt and ThieleNet, uses a thick coax cable tMt can
`run as far as 1,640 feet without using repeaters. Attachment is made by damping a rransceiver onto the
`thick coax, which contains another cable that is connecu:d [Q the adapter card via a IS-pin socket (AUI
`parr).
`"
`Thin Ethernet (10Base2), also called ThinNer and ChcapcrNct, uses a thinner, less-expensive coax that
`is 'callier to connect but has a limitation of 607 feer per ~gmcnt. ThinNe{ uses T-type BNC cannecrors,
`and the transceivers are built into th~ adapter cards.
`
`lWlsted Pair Ethernet
`10BassT and 100BaseT are the most
`popUlar Ethernets. All nodes connect to
`a central hub using twisted pair wires and
`RJ-45 connectors.
`
`The OrIginal Ethernet
`'Thick" Ethernet (106ase5) was the first
`Ethernet and uses a bus topology.
`Transceivers connect
`the network
`adapters to a common coaxial cable.
`They often use a vampire tap that 'bites'
`Into the coax.
`
`W1lJ1/l
`
`AUI(Oe.15
`connector)
`
`310
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`Ethernet adapter, Ethernet card
`
`Thin Ethernet
`"Thin" Ethernet (10Base2) is a variation of
`"thick' Ethernet and uses a thinner coaxial
`cable that Is attached to each node using BNC
`T-connectors.
`
`BIlCo
`
`Twisted pair Ethernet (IOB=n uses economical telephone wiring and standard RJ-45 conneetots.
`often taking ndvll.Iltnge ofinstaJlec( wires in a building.
`It i. wired in a scar configUration and requires a
`hub. FllSt Emerncr (lOOBasen is similat. but uses two different twisted pair configurations (see
`lOOBauT).
`Fiber Optic Ethernet (lOBaseF and 100BascPX) is lmpervious to cxIernaJ radiation and is often used
`to extend Ethernet segments up to 1.2 mil..... Specl!1C2tions exist for compiete lib"r optic lletwOrks as well
`as backbone implernenrations. FOIRL (Fiber Optic Repe.ac"r Link) WlL'l
`lUI c:nrlier standard that is limited
`(0 .G miles elisranee.
`Ethernet crammits variable length frames from 7'). to 1518 bytes in length, each cont.uning a header
`with the :uidtcsses of'the source and desunation stations and a trailer that contains error corrl!Ction data.
`Higher-level prorocols. such as lP and IPX. fragment long messages into.the frame siu: required by the .
`Ethernet network being empJoyed.
`Ethernet uses tbe CSMNCD technology to broadca~t eaclLframe on~o the physical meelium (wire,
`fibe.r, etc.). All scations attached to the Ethe.rnet lire Rlistcnil\g.RllDd the nation wllh the matching
`destinuion ;ddrcs& accepa the &..me and checks for errors. Ethernet is .. dara link protocol (MAC I;yer
`protocol) and funetlon$ at l:tyw 1 and 2 of d,e OS! model.
`EthcfocnY:l.S Invented by Robert Mctc.alfe and David Boggs at Xerox PARC in 1973. whieh lirH ran at
`2.94 Mbps. Metcalfe later joined Digital where he facilitated :l joiot venru.re between Digital, {ntd and
`Xerox to collaborate further on Ethetnet. Version twas £1nw'l.Cd in 1980, and produces shipped in the
`following y=.
`In 1983, the lEEE approved the Ethernet 802.3 st:llJldard. See lOOBllSeT. Gigabit Ethernet
`and switched. Ethtrntt.
`
`ETRE~T LIMITATIONS
`
`Type
`COAX (bus topology)
`10Base5 "thick"
`10Base2 "thin"
`
`Maximwa
`Devlce.
`
`1640 ft.
`607 ft.
`
`(500 m)
`(185 m)
`
`100
`30
`
`TWISTED PAIR (star topology)
`328 it.
`10EaseT
`100BaseT
`328 ft.
`FIBER (star topology)
`FOIRL
`lOBaseF
`100BaseFX moltimode
`lOOBaseFX single-mode
`
`.6 mi.
`L 2 mi.
`1.2 mi.
`6 mi.
`
`(100 tn)
`(100 m)
`
`(1 km)
`(2 km)
`(2 km)
`(10 kin)
`
`1
`1
`
`1
`1
`1
`1
`
`Ethernet adapter, Ethernet card
`The Ethernet hudware required to attach to an Ethernet network. It typically resides on an expansion
`board, but Is sometimes bulle into the motherboard. An Ethetnet adapter is required in each client and
`server. See Ethernet and network ada/tn". .
`
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`interpret
`
`interpret
`To run a program one line at a rime. Each line of source language is translated into machine language
`and then executed.
`Interpreter
`II
`A IUgh-levd prog=ming lmguage tram:!ator that translate JI.l1d rullS dle program at the r.unc tLme.
`uansl,w:s one program sta=ent ioto machine l-anguage, eu.cure;; it. men proceeds to tbe nut st-a.tcmcnr.
`This differs &om rCgular aecumble programs that are presenred 10 the compulCI as binary-coded
`instructions. Interprelr.d programs relJl.:l.ill in roe same sourl;C Imguagc format the prog=mer wrote in:
`as lat files. nor machine Imguage 6Jes.
`Inre<pICted programs run dowel than their compiler counrerpartS.
`'Wh= me compiler tn.nslates
`r.be entire program before il is run. interpreters translate a line at a rime while the program is run.
`However. ir is very collveniem ro write lUI imerprercU program. since a single Jjne of epde c:w be resred
`interactively.
`lnterpreted programs must always be run with the interpreter. For example. in oroer to run a BASIC
`or dBASE. Rrogram, the BASIC or dBASE imerpreter must be in the tafgtt computer.
`.
`Ifa lans",,&e can be both interpreled and compiled, a program m:l.Y be developed with rhe interpreter
`fOI <::lJle of resting and debugging and later compiled for produ.ctlon use. See rompiln- for illustration.
`Interpretive language
`A programming language thar requires an interpreter to run it.
`Interprocess communication
`See lPC.
`,interrecord gap
`The empty space genemred between blocks of data on older
`magnetic rapes. which is erC:l.ted by the $Carting and stOpping of the
`red, Tod2.y's drives do not use erase heads, and th~ stOp-start areas
`are filled with padded block.! of clu:l. or special frequencies.
`Interrogate
`(1) To search, sum or coUOt r~cords in a file. See qUtry.
`(2) To t~t r.b~ condition or statuS of a terminal or computel
`system.
`interrupt
`A signal thar gees the! attentiob of the CPU a.nd is u$~lI1ly
`g=c:rllted wlwl IlO is required. For example, hardware interrupts
`arc generated when ll. kc:y is pressed or when the mouse is moved.
`Softwue interrupts :uc generated by 0. program requiring disk
`input or ourpur.
`An internal timer may continually interrupt the <:omputer
`several times per second [Q keep the time of day ament or for
`timesharing purposes.
`When an interrupt occurs, control is transferred to the
`opera.ting system. which determines che action to be taken. Interrupts are prioritized; the higher the
`priorhy. dl~ weer che interrupt will be serviced.
`Interrupt·driven
`A computer or communiations network mat uses interrupts.·
`Interrupt latency
`The time it take to service an interrupt. It becomes a critical factor when servicing realtime funcrions
`such as a commUhications line. See UART overrun.
`Interrupt mask
`'
`An internal switch serting roat concrols whether an interrupt can be processed or not. The mask is a .
`bit th;a,l is tUIned on and off by the program.
`
`Gaps
`Interrecord Gaps,
`In the old days, the gaps
`between the records were
`often larger than the blocks
`of data.
`
`468
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`Computer Desktop Encyclopedia
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`HP-ACC-00976206
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`

`
`-
`
`National Semiconductor
`
`exchmge pointS widlln the U.S. National ISPs generaUy connect at all four of the original ones and all
`MAF.s. This is known as public poamg.
`In addition, d= to the congestion at these exclumges, huge ISPs peer privatdy and interconnecc wich
`<::Ich other lit many other point! duoughour ehe councrywb.cre equipment at bOth complUties is
`conveniendy loeared. Dropping the packet off eadid: to che dcsriruu:ion ba.ckbone eliminates considerable
`traffic. Privare peering enables I..rger TSPs Ul move m.ffic morc dEciently cb.ll.ll smaller ones. Sec peerhlg
`and CIX
`
`NAPLPS
`(North American Pre.'cnr.don-I.cvd Pro tow! Syntax) An ANSI-st:Uldard proroce! for videotex al1d
`rderen.
`It compresses data for uommission over I'mrow-bandwidch Jin~ and requila decompression on
`me receiving end. PRODIGY uses chis formar for rransmitring :ll1d displaying some oria graphics.
`narrowband
`In communications, transmission rates from SO bps to 64 Kbps. Earlier uses of the term referred to
`2,400 bps Ot less or eo sub-voice grade transmission from SO co 150 bps. Contr:lSt with wiJeband:md
`broadband.
`.
`
`narrowcast
`To transmit dam to selected individuals. Contrast with broadca.rt.
`
`NAS
`.
`(1) (Network AttaChed Storage) A specialized me server thac connectS to the nerwork. It uses
`rraditional LAN protoCOls such ~ Ememer and TCPlIP lIDd proces= only file JlO request! sucb :IZ NPS
`(UNIX) wd 5MB (DOSlWlOdOW!). See SAN for deralls on srofllge networks.
`(2) (Nelwork Applicacion Support) Digir:tl's implemenrorion of open sysrems, which provides
`rnndards--b~s«! software rba. allows ~ variety of workStllrions (VMS, U.IJ1UX, Sun, DOS. Windows, OSI
`2, Mac, etc.) to interfu:e via VAX wd ULTRlX seryers.
`.
`
`NASI
`(1) (NetWare Asynchronous Servia: InlerfiLce) A prorocol from Novell for connecting to modems in a
`cornmunic:arlons server. Ir w.>.s derived from th~ NCSTl'rorocol. NASI provides more advanced features
`It allows a specific modem or line to be chosen. Ir frees
`rhan the common inr 14 (intenupt 14) memod.
`me call more quickly, and it rransfers dara mote efficiendy.
`(2) (National Association of Systems Imegrarors, Walpole. MA, www.nasi-info.com) An ·organil.3tion
`ofmore mlln 10,000 members founded in 1991. dedicated to exchanging up-to-date informacion on
`members' products and services. Ito annual Computer Indu.srry Bl.lying Guide in prim a.nd on disk
`includes supplim and services.
`
`NAT
`(Nerwork Address Tra.nsJ~rion) An J:ETl'standud rb:u allows an organirocion rO present itsdf to the
`Internet with one address. NAT convem the address of each LAN node inro one IF address for the
`Inrernec and vie<: versa. It also $Crves .5 it fjro;wall by keeping individual IP addresses hidden from the
`outside world.
`National Cristina Foundation
`(Narional Cri~tin:l Foudacion, Sramford, cr. www.crutina.org) A not-far-profic public cJltuiry that
`seeks donarions of used or cxccs$ compurca. FOllDded in 1984 by YVerte Mamn and Brue<: McMahan. it
`was OIuoed in honor of McMwan's daughrcr. CrisTina, who has oclebraJ p.usy. DOMtions are directed rO
`programs mat rdJabiUmre people with disabilities. !CudeDt' at risk of fuiJinll and me economically
`disadvltlU:tged. The foundation las helped hundreds of thousands 'Of individu:tls in the U.S. wd lLbroad.
`See how to dondte old equipment.
`
`National Semiconductor
`(National Semiconductor Corporarion. Santa CllLra. CA. www.narlonal.com) A m:tjorsemiconductor
`monumcrurtr chat provides system-level products for telecommunicarioll.'i, desktop computers.
`~utomobilcs. consumer produCtS and the milir:uy. Founded in 1959 in Danbury, CT, Narional
`Semiconductor was in rhe fore&onr of me first cransistors and incepted circuies. OVeJ: the years. ir has
`become known for irs analog and mixed mode signalling devi=. In 1987. it acquired Faircl1Ud
`Semiconductor, which it sold in 1997, the same .yClll" in merged with Cyrix Corporation.•
`
`Computer Desktop Encyclopedia
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`HP-ACC-00976207
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`

`
`POP server
`
`Polish notation
`A merhod for expressing a sequence of calculations developed by the Polish logician lan Lukasiewicz in
`1929. For example, a (b+c) would be expressed as *a+bc. In reverse Polish, it would be abc+*.
`polling
`A communications technique dlar determines wh~ a terminalls rady co send clara. The computer
`eominUlllly imCrrOg3tCS its connected rermlruUs in a round robin sequence. If a terminal has darn, to send,
`ir sends back an llcknowledg=ent and rJ1C transmission bcgins. COnlI;l.It wirl! Interrupt-drjvm, in wbkb
`me tcm'lina1 generates a siglU1 when it has clara to send.
`polling cycle
`One round in which each and every =milU1 connecred to che compurer at controller has been polled
`once.
`polycarbonate
`A category of p[mic materials, used to make myriads of products. including CDs and CD-ROMs.
`polygon
`.
`In computet graphics, a multi-sided object that can be filled with color or moved around as a single
`eotiey. See triangle.
`polyhedron
`A six- or more-sided object. A group of connected polygons;
`polyline
`In romputer graphics, a single emiry that is made up
`of a series of connected lines.
`polymorphic tweening
`See tweening.
`polymorphIc virus
`A virus that changes its binary pattern each dme it infects a new file ro keep it from being identified.
`See It(alth vil'UI.
`polymorphism
`Meaning many shapes. In object technology, the ability of a generalized request (message) to produce
`different results based on the object that it is sent to. See polymorphic "irut.
`.
`polyphonic
`The abillry to play back some number of music~ notes simultaneously. For example, 16-voice
`polyphony means a toral of 16 notes. or waveforms, can be played concurrently.
`POP
`(point of l'rese.nce) The polm at which a line from a long distaJ'ltc arrier (!XC) connects to the line
`of d\e 10cuJ telephone company or to the user if the local company is not i.nvolved. For online servicc:s :tnd
`Inrerner providers. che POP is rhe local exchange users dial imo via. modtm. See POP3, POP-J wdpluhl
`pop.
`POP-1
`{package for Online Programming} The am of a family of programming languages introduced in
`England in the mid 1960,.. It used reverse polish notation. Successors were POP.2, POP-9X, POP·10,
`.
`POP.11, POPCORN, 1'0P++. POPWG and POPLER.
`
`Polygon
`
`POP3
`(Post Office Protocol 3) A stlll\dard mail server commonly used on the Internet, It provides a message
`Slorc th,u holds incoming c-mall ulldl Users log on and download ir. POP3 is a simple sysrem with little
`selectivity. All pcnding messages and attachments a.re downlo:u1ed at the same rime. POP3'uses the
`SMTP mC5Sllging protocol. See IMAP and ma/aging fjIttm.
`POP server
`A server char implements me Post Office Prorocol See POP!).
`
`Computer Desktop Encyclopedia
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`
`primary key
`
`primary key
`An indexed Reid that maintains the primary sequence of the file/cable.
`primary storage
`The computer's internal memory (RAM). Contrast with stcondttry ttorlZgt.
`
`primitive
`(1) In computer graphics, a graphics dement that is u~ed :l.$ a building block for creating images, such
`:l.$ a point, line, arc. cone or sphere.
`(2) In programming. a fundamental instruction. statement or operation.
`(3) In microprogramming, a microinstruction. or elementary machine opera~ion.
`print column
`A column ofdata on a printed report that may be subtotalled or totalled. Print columns are the heart
`of a report writer's description.
`
`printed circuit board
`A flat board that holds chips and other electronic components. The board is made of reinforced
`flberglas:s or plastic and inrerconnl!CfS components via copper pathways. The main printed circuit board
`io a system is called II. system board or motherboard. while smaller ones that plug into the slots in the main
`board are called board; or card;.
`The printed circuit board of the 1960s connected discrete components together. The circuit board of
`the 1990s interconnects chips, each containing hundreds of thousands and millions of elementary
`components.
`The ·printed" circuit is rcally an etched cirtuit. A copper foil is placed over the glass or plastic base
`and covered with a phororesi$t. Light is shined through a negative image of the circuit paths Onto the
`photoresist, hardening the arCllS char will remain after erching. When passed through an acid bath. the
`unhardened areas arc W;l.Shed away. A similar process cr....reG the mieromlniaruri7.cd circuit< on a chip (see
`chip).
`printer
`A device that converts computer output into printed images. Following is an overview of the various
`technologies.
`For more derails, look u