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1、…………………………………………………………最新精品资料推荐……………………………………………………PassageADataCommunicationsTherapidgrowthofdatacommunicationshasbeeninfluencedprimarilybytheincreasingneedtomoveinformationtoandfromcomputers.Moderntime-sharedcomputerscancommunicatewithmanydatastationssimultaneously.Other
2、formsofdatatransmissionwhichthetelephoneandtelegraphlinesarecalledupontohandlearebatchdatatransmission,real-timetransmission(asinthecaseofairlinereservationsystems),bankingandcreditdata,man-computerconversationwiththeaidofgraphics,datacollectionsystemsandautomaticmeterre
3、ading.Thecombinationofcomputersanddatacommunicationplacessuchnewrequirementsonthesystems,whichmusthandlethem,thatonecanrefertothembetterasteleprocessingratherthantelecommunications.[1]…………………………………………………………最新精品资料推荐……………………………………………………17…………………………………………………………最新精品资料推荐……………
4、………………………………………Teleprocessingstartedwiththeairlinereservationsystems,wherethedistributionofcomputerdataisnotasimportantasthemaintenanceofaninventoryofseatsforthewholesystemandtheabilitytoaccesssuchaninventoryrapidlyatanumberofdistantpoints.Anotherexampleisthatofthebanks,
5、whodesiredtocentralizetheiraccountingandprovideaccesstoacentralfileforalltheirbranches.Basically,therearethreereasonsforthedevelopmentofteleprocessingsystems:therequirementforcentralizedfiles,theneedtodistributecomputerservicesandtheadvantagegainedbyhavingflexibilityinlo
6、cationoftheoperatingstaffwhichutilizesthesystem.…………………………………………………………最新精品资料推荐……………………………………………………17…………………………………………………………最新精品资料推荐……………………………………………………Initially,boththeairlineandbankingoperationscanbeestablishedonaprivatebasis,whichwouldminimizetheneedforswitchingoperatio
7、ns.Butinbothcases,theneedtoexpandbeyondprivateoperationssoonarises.Inthecaseoftheairlines,theneedarisestoaccessthefacilitiesofotherairlines;andinthecaseofthebanks,certaincommondatafacilitiesmaybesharedwithotherbanks.Eventhoughprivatenetworksmaysufficeformanyservices,then
8、eedtoprovidedatacommunicationsbetweenurbancentersleadstoregionalandnationalnetworks.IntheU.S.,theBellSy