計算機專業(yè)英語ch7網(wǎng)絡(luò)

Unit1Network

o7■工Introductiontonetwork

o7.2Protocol

o7.3Hardware

o7.4Topology

下一頁

第7單元網(wǎng)絡(luò)

。7.1網(wǎng)絡(luò)介紹

。7?2協(xié)議

o7.3硬件

。7.4拓?fù)浣Y(jié)構(gòu)

上一頁

7.1Introductiontonetwork

oNetworkisagroupoftwoormorecomputer

systemslinkedtogether.Therearemanytypes

ofcomputernetworks,including:

oLocal-AreaNetworks(LAN):Thecomputersare

geographicallyclosetogether(thatis,inthe

samebuilding).

oWide-AreaNetworks(WAN):Thecomputers

arefartherapartandareconnectedby

telephonelinesorradiowaves.

oMetropolitan-AreaNetworks(MAN):Adata

networkdesignedforatownorcity.

下一頁返叵

7.1Introductiontonetwork

oInadditiontothesetypes,thefollowing

characteristicsarealsousedtocategorize

differenttypesofnetworks:

oTopology:Thegeometricarrangementofa

computersystem.Commontopologiesinclude

abus,starandring.

oProtocol:Theprotocoldefinesacommonsetof

rulesandsignalsthatcomputersonthe

networkusetocommunicate.Oneofthemost

popularprotocolsforLANsiscalledEthernet.

AnotherpopularLANprotocolforPCsisthe

IBMtoken-ringnetwork.

上一頁下一頁返叵

7.1Introductiontonetwork

oArchitecture:Networkscanbebroadly

classifiedasusingeitherapeer-to-peeror

client/serverarchitecture.

oComputersonanetworkaresometimescalled

nodes.Computersanddevicesthatallocate

resourcesforanetworkarecalledservers.To

connecttwoormorecomputerstogetherwith

theabilityistocommunicatewitheachother.

上一頁下一頁返叵

7.1Introductiontonetwork

oKeywords

oLocal-AreaNetworks(LAN)局域網(wǎng)

oWide-AreaNetworks(WAN)廣域網(wǎng)

ometropolitan-areanetworks(MAN)城域網(wǎng)

ocharacteristic特征

ocategorize將...分類

otopology拓?fù)?/p>

ogeometric幾何的

oarrangement布置，方案

obus總線型

ostar星型

上一頁下一頁返叵

7.1Introductiontonetwork

oring環(huán)型

oprotocol協(xié)議

otoken-ringnetwork令牌環(huán)網(wǎng)

oarchitecture體系結(jié)構(gòu)

onode節(jié)點

oallocate分配

oresource資源

上一頁返叵

7.2Protocol

oAprotocolisasetofrulesthatgovernsthe

communicationsbetweencomputersona

network.Theserulesincludeguidelinesthat

regulatethefollowingcharacteristicsofa

network:accessmethod,allowedphysical

topologies,typesofcablingandspeedofdata

transfer.

oThemostcommonprotocolsare:FastEthernet,

EigabitEthernet,LocalTalk,TokenRing,FDDI,

ATMandEthernet.

下一頁返叵

7.2Protocol

oTheEthernetprotocolisbyfarthemostwidely

used.Ethernetusesanaccessmethodcalled

CSMA/CD(CarrierSenseMultiple

Access/CollisionDetection).Thisisasystem

whereeachcomputerlistenstothecable

beforesendinganythingthroughthenetwork.

Ifthenetworkisclear,thecomputerwill

transmit.Ifsomeothernodeisalready

transmittingonthecable,thecomputerwill

waitandtryagainwhenthelineisclear.

Sometimes,twocomputersattempttoa

上一頁下一頁返叵

7.2Protocol

transmitatthesameinstant.Whenthis

happensacollisionoccurs.Eachcomputerthen

backsoffandwaitsrandomamountoftime

beforeattemptingtoretransmit.Withthis

accessmethod,itisnormaltohavecollisions.

However,thedelaycausedbycollisionsand

retransmittingisverysmallanddoesnot

normallyaffectthespeedoftransmissionon

thenetwork.

上一頁下一頁返叵

7.2Protocol

oTheEthernetprotocolallowsforlinearbus,

starandtreetopologies.Datacanbe

transmittedoverwirelessaccesspoints,

twistedpair,coaxialcableorfiberopticcable

ataspeedof10Mbpsupto1,000Mbps.

oFastEthernet

oToallowforanincreasedspeedof

transmission,theEthernetprotocolhas

developedanewstandardthatsupports100

Mbps.ThisiscommonlycalledFastEthernet.

FastEthernetrequirestheuseofdifferent,

上一頁下一頁返叵

7.2Protocol

omoreexpensivenetworkconcentrators/hubs

andnetworkinterfacecards.Inaddition,

category5twistedpairorfiberopticcableis

necessary.FastEthernetisbecomingcommon

inschoolsthathavebeenrecentlywired.

oGigabitEthernet

oThemostrecentdevelopmentintheEthernet

standardisaprotocolthathasatransmission

speedof1Gbps.GigabitEthernetisprimarily

usedforbackbonesonanetworkatthistime.

上一頁下一頁返叵

7.2Protocol

Inthefuture,itwillprobablybeusedfor

workstationandserverconnectionsalso.It

canbeusedwithbothfiberopticcablingand

copper.Thel,OOOBase-TX,thecoppercable

usedforGigabitEthernet,becometheformal

standardin1999.

oLocalTalk

oLocalTalkisanetworkprotocolthatwas

developedbyAppleComputer,Inc.for

Macintoshcomputers.Themethodusedby

LocalTalkiscalledCSMA/CA(CarrierSense

上一頁下一頁返叵

7.2Protocol

MultipleAccesswithCollisionAvoidance).

LocalTalkadaptersandspecialtwistedpair

cablecanbeusedtoconnectaseriesof

computersthroughtheserialport.The

Macintoshoperatingsystemallowsthe

establishmentofapeer-to-peernetwork

withouttheneedforadditionalsoftware.With

theadditionoftheserverversionof

AppleSharesoftware,aclient/servernetwork

canbeestablished.

上一頁下一頁返叵

7.2Protocol

oTheLocalTalkprotocolallowsforlinearbus,

starandtreetopologiesusingtwistedpair

cable.AprimarydisadvantageofLocalTalkis

speed.Itsspeedoftransmissionisonly230

Kbps.

oTokenRing

oTheTokenRingprotocolwasdevelopedbyIBM

inthemid-1980s.Theaccessmethodused

involvestoken-passing.InTokenRing,the

computersareconnectedsothatthesignal

travelsaroundthenetworkfromonecomputer

toanotherinalogicalring.Asingleelectronic

上一頁下一頁返叵

7.2Protocol

tokenmovesaroundtheringfromone

computertothenext.Ifacomputerdoesnot

haveinformationtotransmit,itsimplypasses

thetokenontothenextworkstation.Ifa

computerwishestotransmitandreceivesan

emptytoken,itattachesdatatothetoken.The

tokenthenproceedsaroundtheringuntilit

comestothecomputerforwhichthedatais

meant.Atthispoint,thedataiscapturedby

thereceivingcomputer.TheTokenRing

protocolrequiresastar-wiredringusing

twistedpairorfiberopticcable.Itcanoperate

上一頁下一頁返叵

7.2Protocol

oattransmissionspeedsof4Mbpsor16Mbps.

DuetotheincreasingpopularityofEthernet,

theuseofTokenRinginschoolenvironments

hasdecreased.

oFDDI

oFiberDistributedDataInterface(FDDI)isa

networkprotocolthatisusedprimarilyto

interconnecttwoormorelocalareanetworks,

oftenoverlargedistances.Theaccessmethod

usedbyFDDIinvolvestoken-passing.FDDI

usesadualringphysicaltopology.

Transmissionnormallyoccursononeofthe

上一頁下一頁返叵

7.2Protocol

rings;however,ifabreakoccurs,thesystem

keepsinformationmovingbyautomatically

usingportionsofthesecondringtocreatea

newcompletering.AmajoradvantageofFDDI

isspeed.Itoperatesoverfiberopticcableat

100Mbps.

oATM

oAsynchronousTransferMode(ATM)isa

networkprotocolthattransmitsdataata

speedof155Mbpsandhigher.ATMworksby

上一頁下一頁返叵

7.2Protocol

otransmittingalldatainsmallpacketsofafixed

size;whereas,otherprotocolstransfer

variablelengthpackets.ATMsupportsa

varietyofmedia,suchasvideo,CD-quality

audioandimaging.ATMemploysastar

topology,whichcanworkwithfiberopticas

wellastwistedpaircable.

oATMismostoftenusedtointerconnecttwoor

morelocalareanetworks.Itisalsofrequently

usedbyISPCInternetServiceProviders,to

utilizehigh-speedaccesstotheInternetfor

上一頁下一頁返叵

7.2Protocol

theirclients.AsATMtechnologybecomesmore

cost-effective,itwillprovideanothersolution

forconstructingfasterlocalareanetworks.

oKeywords

ogovern管理，控制

oguideline方針，指導(dǎo)方針

oregulate管理，調(diào)整

oCSMA/CD

上一頁下一頁返叵

7.2Protocol

o(CarrierSenseMultipleAccess/Collision

Detection)載波偵聽多路訪問/沖突檢測

otransmit傳送

ocollision沖突，碰撞

oretransmit再傳送

odelay延遲

owirelessaccesspoint無線網(wǎng)關(guān)

otwistedpair雙絞線

ocoaxialcable同軸電纜

上一頁下一頁返叵

7.2Protocol

ofiberopticcable光纜

oconcentrator集線器

ohub集線器

onetworkinterfacecard網(wǎng)絡(luò)接口卡

obackbone基干，中樞，主干線

ocoppercable銅電纜

oCSMA/CA

o(CarrierSenseMultipleAccesswithCollision

Avoidance)載波偵聽多路訪問/避免沖突

oserialport串行口

上一頁下一頁返叵

7.2Protocol

oestablishment建立

ocapture捕獲

oenvironment環(huán)境

oFDDI(FiberDistributedDataInterface)光纖分布

式數(shù)據(jù)接口

ointerconnect互連

oATM(AsynchronousTransferMode)異步傳輸模式

oISP(InternetServiceProvider)因特網(wǎng)月艮務(wù)提供商

上一頁返叵

7.3Hardware

oNetworkinghardwareincludesallcomputers,

peripherals,interfacecardsandother

equipmentneededtoperformdata-processing

andcommunicationswithinthenetwork.

oFileServers

oAfileserverstandsattheheartofmost

networks.Itisaveryfastcomputerwitha

largeamountofRAMandstoragespace,along

withafastnetworkinterfacecard.The

networkoperatingsystemsoftwareresideson

thiscomputer,alongwithanysoftware

applicationsanddatafilesthatneedtobe

shared.

下一頁返叵

7.3Hardware

oThefileservercontrolsthecommunicationof

informationbetweenthenodesonanetwork.

Forexample,itmaybeaskedtosendaword

processorprogramtooneworkstation,receive

adatabasefilefromanotherworkstation,and

storeanE-mailmessageduringthesametime

period.Thisrequiresacomputerthatcanstore

alotofinformationandshareitveryquickly.

Fileserversshouldhaveatleastthefollowing

characteristics:

上一頁下一頁返叵

7.3Hardware

?800megahertzorfastermicroprocessor

(Pentium3or4,G4orG5).

?Afastharddrivewithatleast120gigabytesof

storage.

?ARAID(RedundantArrayofInexpensiveDisks)

topreservedataafteradiskcasualty.

?Atapeback-upunit(i.e.DAT,JAZ,Zip,orCD-

RWdrive).

?Numerousexpansionslots.

?Fastnetworkinterfacecard.

?Atleastof512MBofRAM.

上一頁下一頁返叵

7.3Hardware

oWorkstations

oAlloftheusercomputersconnectedtoa

networkarecalledworkstations.Atypical

workstationisacomputerthatisconfigured

withanetworkinterfacecard、networking

softwareandtheappropriatecables.

Workstationsdonotnecessarilyneedfloppy

diskdrivesbecausefilescanbesavedonthe

fileserver.Almostanycomputercanserveas

anetworkworkstation(SeePIC7.1),

上一頁下一頁返叵

7.3Hardware

oNetworkInterfaceCards

oThenetworkinterfacecard(NIC)providesthe

physicalconnectionbetweenthenetworkand

thecomputerworkstation.MostNICsare

internal,withthecardfittingintoanexpansion

slotinsidethecomputer.Somecomputers,

suchasMacClassics,useexternalboxeswhich

areattachedtoaserialportoraSCSIport.

Laptopcomputerscannowbepurchasedwith

anetworkinterfacecardbuilt-inorwith

networkcardsthatslipintoaPCMCIAslot.

上一頁下一頁返叵

7.3Hardware

oNetworkinterfacecardsareamajorfactorin

determiningthespeedandperformanceofa

network.Itisagoodideatousethefastest

networkcardavailableforthetypeof

workstationyouareusing.

oThethreemostcommonnetworkinterface

connectionsareEthernetcards>LocalTalk

connectorsandTokenRingcards.Accordingto

aInternationalDataCorporationstudy,

Ethernetisthemostpopular,followedby

TokenRingandLocalTalk(Sant'Angelo,R.

(1995).NetWareUnleashed,Indianapolis,IN:

SamsPublishing).

上一頁下一頁返叵

7.3Hardware

oEthernetCards

oEthernetcardsareusuallypurchased

separatelyfromacomputer,althoughmany

computers(suchastheMacintosh)now

includeanoptionforapre-installedEthernet

card.Ethernetcardscontainconnectionsfor

eithercoaxialortwistedpaircables(orboth)

(SeePIC7.2),

oIfitisdesignedforcoaxialcable,the

connectionwillbeBNC.Ifitisdesignedfor

twistedpair,itwillhaveaRJ-45connection.

SomeEthernetcardsalsocontainanAUI

connector.Thiscanbeusedtoattachcoaxial,

上一頁下一頁返叵

7.3Hardware

twistedpairorfiberopticscabletoanEthernet

card.Whenthismethodisusedthereisalways

anexternaltransceiverattachedtothe

workstation.

oLocalTalkConnectors

oLocalTalkisApple'sbuilt-insolutionfor

networkingMacintoshcomputers.Itutilizesa

specialadapterboxandacablethatplugsinto

theprinterportofaMacintosh.Amajor

disadvantageofLocalTalkisthatitisslowin

comparisontoEthernet.MostEthernet

上一頁下一頁返叵

7.3Hardware

oconnectionsoperateat10Mbps(Megabitsper

second).Incontrast,LocalTalkoperatesat

only230Kbps(or0.23Mbps)(SeePIC7.3).

oTokenRingCards

oTokenRingnetworkcardslooksimilarto

Ethernetcards.Onevisibledifferenceisthe

typeofconnectoronthebackendofthecard.

TokenRingcardsgenerallyhaveaninepin

DINtypeconnectortoattachthecardtothe

networkcable.

上一頁下一頁返叵

7.3Hardware

oSwitch

oAconcentratorisadevicethatprovidesa

centralconnectionpointforcablesfrom

workstations,serversandperipherals.Ina

startopology,twisted-pairwireisrunfrom

eachworkstationtoacentralswitch/hub.

Mostswitchesareactive.Thatisthey

electricallyamplifythesignalasitmovesfrom

onedevicetoanother.Switchesnolonger

broadcastnetworkpacketsashubsdidinthe

past,theymemorizeaddressingofcomputers

andsendtheinformationtothecorrect

locationdirectly.Switchesare:

上一頁下一頁返叵

7.3Hardware

oUsuallyconfiguredwith8,12or24RJ-45ports,

oOftenusedinastarorstar-wiredringtopology,

oSoldwithspecializedsoftwareforport

management.

oRepeaters

oSinceasignallosesstrengthasitpassesalong

acable,itisoftennecessarytoboostthe

signalwithadevicecalledarepeater.The

repeaterelectricallyamplifiesthesignalit

receivesandrebroadcastsit.Repeaterscanbe

separatedevicesortheycanbeincorporated

上一頁下一頁返叵

7.3Hardware

intoaconcentrator.Theyareusedwhenthe

totallengthofyournetworkcableexceedsthe

standardssetforthetypeofcablebeingused,

oAgoodexampleoftheuseofrepeaterswould

beinalocalareanetworkusingastar

topologywithunshieldedtwisted-paircabling.

Thelengthlimitforunshieldedtwisted-pair

cableis100meters.Themostcommon

configurationisforeachworkstationtobe

connectedbytwisted-paircabletoamulti-port

activeconcentrator.Theconcentrator

上一頁下一頁返叵

7.3Hardware

amplifiesallthesignalsthatpassthroughit

allowingforthetotallengthofcableonthe

networktoexceedthe100meterslimit.

oBridges

oAbridgeisadevicethatallowsyoutosegment

alargenetworkintotwosmaller,more

efficientnetworks.Ifyouareaddingtoan

olderwiringschemeandwantthenew

networktobeup-to-date,abridgecanconnect

thetwo.

上一頁下一頁返叵

7.3Hardware

oAbridgemonitorstheinformationtrafficon

bothsidesofthenetworksothatitcanpass

packetsofinformationtothecorrectlocation.

Mostbridgescan“l(fā)isten”tothenetworkand

automaticallyfigureouttheaddressofeach

computeronbothsidesofthebridge.The

bridgecaninspecteachmessageand,if

necessary,broadcastitontheothersideofthe

network.

上一頁下一頁返叵

7.3Hardware

oThebridgemanagesthetraffictomaintain

optimumperformanceonbothsidesofthe

network.Youmightsaythatthebridgeislike

atrafficcopatabusyintersectionduringrush

hour.Itkeepsinformationflowingonboth

sidesofthenetwork,butitdoesnotallow

unnecessarytrafficthrough.Bridgescanbe

usedtoconnectdifferenttypesofcabling,or

physicaltopologies.Theymust,however,be

usedbetweennetworkswiththesame

protocol.

上一頁下一頁返叵

7.3Hardware

oRouters

oAroutertranslatesinformationfromone

networktoanother;itissimilartoa

superintelligentbridge.Routersselectthebest

pathtorouteamessage,basedonthe

destinationaddressandorigin.Theroutercan

directtraffictopreventhead-oncollisions,and

issmartenoughtoknowwhentodirecttraffic

alongbackroadsandshortcuts.

上一頁下一頁返叵

7.3Hardware

oWhilebridgesknowtheaddressesofall

computersoneachsideofthenetwork,

routersknowtheaddressesofcomputers,

bridges,andotherroutersonthenetwork.

Routerscaneven"listen"totheentire

networktodeterminewhichsectionsare

busiest-theycanthenredirectdataaround

thosesectionsuntiltheyclearup.

oIfyouhaveaschoolLANthatyouwantto

connecttotheInternet,youwillneedto

purchasearouter.Inthiscase,therouter

上一頁下一頁返叵

7.3Hardware

servesasthetranslatorbetweenthe

informationonyourLANandtheInternet.It

alsodeterminesthebestroutetosendthe

dataovertheInternet.Routerscan:

?Directsignaltrafficefficiently.

?Routemessagesbetweenanytwoprotocols.

?Routemessagesbetweenlinearbus,starand

star-wiredringtopologies.

?Routemessagesacrossfiberoptic,coaxial

cableandtwisted-paircabling.

上一頁下一頁返叵

7.3Hardware

oKeywords

oequipment設(shè)備

ofileserver文件服務(wù)器

oshare共享

oRAID(RedundantArrayofInexpensiveDisks)

廉價磁盤冗余陣列

上一頁下一頁返叵

7.3Hardware

opreserve保護

ocasualty故障

oback-up備份

oexpansionslot擴展槽

oNIC(networkinterfacecard)網(wǎng)絡(luò)接口卡

ofitinto放進

oInternationalDataCorporation國際數(shù)據(jù)公司

otransceiver收發(fā)器

oadapter適配器

operipheral外設(shè)

上一頁下一頁返叵

7.3Hardware

oamplify放大

osignal信號

opacket包，數(shù)據(jù)包，數(shù)據(jù)分組，分組報文

orepeater中繼器

ounshieldedtwisted-paircable非屏蔽雙絞線

obridge網(wǎng)橋

olisten監(jiān)聽

ofigureout算出

oinspect審查，檢查

ooptimum最佳

上一頁下一頁返叵

7.3Hardware

orouter路由器

odestination目的

oorigin源

oshortcut快捷方式，快速，捷徑

oredirect重定向

osend發(fā)送

oefficiently高效的

oroute路由，路徑，傳遞

上一頁返叵

7.4Topology

oThephysicaltopologyofanetworkrefersto

theconfigurationofcables,computersand

otherperipherals.Physicaltopologyshouldnot

beconfusedwithlogicaltopologywhichisthe

methodusedtopassinformationbetween

workstations.

oThefollowingsectionsdiscussthephysical

topologiesusedinnetworksandotherrelated

topics.

oLinearBus

下一頁返叵

7.4Topology

oAlinearbustopologyconsistsofamainrunof

cablewithaterminatorateachend(SeePIC

7.4),Allnodes(fileserver,workstations,and

peripherals)areconnectedtothelinearcable.

EthernetandLocalTalknetworksusealinear

bustopology.

oAdvantagesofaLinearBusTopology

?Easytoconnectacomputerorperipheraltoa

linearbus.

?Requireslesscablelengththanastartopology,

oDisadvantagesofaLinearBusTopology

上一頁下一頁返叵

7.4Topology

?Entirenetworkshutsdownifthereisabreak

inthemaincable.

?Terminatorsarerequiredatbothendsofthe

backbonecable.

?Difficulttoidentifytheproblemiftheentire

networkshutsdown.

?Notmeanttobeusedasastand-alonesolution

inalargebuilding.

oStar

oAstartopologyisdesignedwitheachnode

(fileserver,workstations,andperipherals)

connecteddirectlytoacentralnetworkhubor

concentrator(SeePIC7,5).

上一頁下一頁返叵

7.4Topology

oDataonastarnetworkpassesthroughthehub

orconcentratorbeforecontinuingtoits

destination.Thehuborconcentratormanages

andcontrolsallfunctionsofthenetwork.It

alsoactsasarepeaterforthedataflow.This

configurationiscommonwithtwistedpair

cable;however,itcanalsobeusedwith

coaxialcableorfiberopticcable.

oAdvantagesofaStarTopology

?Easytoinstallandwire.

?Nodisruptionstothenetworkwhen

connectingorremovingdevices.

上一頁下一頁返叵

7.4Topology

?Easytodetectfaultsandtoremoveparts.

oDisadvantagesofaStarTopology

?Requiresmorecablelengththanalinear

topology.

?Ifthehuborconcentratorfails,nodes

attachedaredisabled.

?Moreexpensivethanlinearbustopologies

becauseofthecostoftheconcentrators.

oTheprotocolsusedwithstarconfigurationsare

usuallyEthernetorLocalTalk.TokenRinguses

asimilartopology,calledthestar-wiredring.

上一頁下一頁返叵

7.4Topology

oStar-WiredRing

oAstar-wiredringtopologymayappear

(externally)tobethesameasastartopology.

Internally,theMAU(multistationaccessunit)

ofastar-wiredringcontainswiringthatallows

informationtopassfromonedevicetoanother

inacircleorring.TheTokenRingprotocol

usesastar-wiredringtopology.

oTree

上一頁下一頁返叵

7.4Topology

oAtreetopologycombinescharacteristicsof

linearbusandstartopologies.Itconsistsof

groupsofstar-configuredworkstations

connectedtoalinearbusbackbonecable(See

PIC7.6).Treetopologiesallowforthe

expansionofanexistingnetwork,andenable

schoolstoconfigureanetworktomeettheir

needs.

oAdvantagesofaTreeTopology

?Point-to-pointwiringforindividualsegments.

?Supportedbyseveralhardwareandsoftware

venders.

上一頁下一頁返叵

7.4Topology

oDisadvantagesofaTreeTopology

?Overalllengthofeachsegmentislimitedby

thetypeofcablingused.

?Ifthebackbonelinebreaks,theentire

segmentgoesdown.

?Moredifficulttoconfigureandwirethanother

topologies.

oKeywords

oterminator終端

oshutdown關(guān)閉，關(guān)機

odataflow數(shù)據(jù)流

上一頁下一頁返叵

7.4Topology

odisruption中斷

ostartopology星型拓?fù)?/p>

oMAU(multistationaccessunit)多站訪問部件

otreetopology樹型拓?fù)?/p>

oScreenEnglish

o1.Stopcompilingafterdetectingaspecified

numberoferrors.

o在檢測到精確的錯誤個數(shù)后停止編譯。

o2.Swapdiskfull!Savefilesandexit.

o交換磁盤滿！保存文件并退出。

上一頁下一頁返叵

7.4Topology

o3.Switchtonotepad,closethisdialogboxand

thentryquittingWindowsagain.

o切換到記事本，關(guān)閉這個對話框，然后再試著退出

WindowSo

o4.Switchingbetweenapplications.

o在應(yīng)用程序之間切換。

o5.Systemhalted.

o系統(tǒng)停止。

o6.Targetcannotbeusedforbackup.

o目標(biāo)盤不能用作備份。

上一頁下一頁返叵

7.4Topology

o7.Theharddriveheadsarenowparked.

o硬盤驅(qū)動器磁頭已復(fù)位。

o8.Thehighlightedselectioncannotbe

compiled.

o不能編譯高亮選擇。

o9.Thenewversionofthisfileisinadifferent

language.

o該文件的新版本使用的語言不同。

o10.Thepermanentswapfileiscorrupt.

o永久交換文件被破壞。

上一頁下一頁返叵

7.4Topology

o11.Theprinteronthisportisoutofpaperor

isnotconnectedtoyourcomputer.

o該端口的打印機缺紙或未與計算機連接。

o12.Therearenoiconsavailableforthe

specifiedfile.

o沒有可用于指定文件的圖標(biāo)。

o13.Targetdiskettebadorunusable.

o目標(biāo)磁盤已損壞或不能使用。

o14.Therearetoomanyfile