Viestinnän ohjausprosessori

Johdanto

Tietoliikenteen ohjausprosessori (CCP)

viestintäohjausprosessori

Foreachhostcomputer,hostcomputerandremoteAdevicethatcontrolsdatatransmissionandexchangebetweendataterminalsandbetweenremotedataterminals.Communicationcontrolprocessorswithdifferentfunctionscanconnectmultiplemaincomputers,communicationlines,andmanyuserterminalsintoacomputercommunicationnetwork,sothattheseuserscanusecomputersinthenetworkatthesametimeandshareresources.Theviestintäohjausprosessoricanusevariouscommunicationprotocolsandinterfaceconventionstoensurethecorrectandeffectivetransmission,transmission,receptionandprocessingofdataandinformation;makeiteasyforthehostcomputeroruserterminaltoaccessthecomputercommunicationnetworkflexibly,withouttheneedtomodifythenetworkforthispurposeDesign,computerdesignanduserterminaldesign;enablethemaincomputertoreleasenetworkcontroltasksandhavemoretimetoperformmainprocessingtasks.

Theviestintäohjausprosessoriisusedtoconnectthecommunicationlineandthehostcomputer(host)orotherdatacommunicationequipment,andmanageallthecommunicationlinesconnectedtothedataterminalequipment(DTE).Eachindependentmulti-channelreceivingportcansimultaneouslyreceivedataofdifferentratesfromdifferentdatacommunicationequipment,andsendittothecommunicationlineaftercentralizedprocessingbyTDM,andsendittotheremotereceivingstation.Thecontrollercaninputcommandsfromtheconsoletoconnect,confirm,andcutoffthelinkcontrolofthelocalmachineortheremotereceivingstation.Theviestintäohjausprosessoriiscomposedoftwoparts,ahardwarecircuitandasoftwarecontrolprogram,andthesoftwareplaysamoreimportantrole.

Perustoiminnot

Typicalcommunicationcontrolprocessingfunctionsoperateaccordingtotherequirementsofcommunicationsoftware,separatingthecommunicationprocessingfunctionfromtheinformationprocessingofthehostcomputer,sothatthehostcomputerdoesnotneedtochangetheterminalType,linetype,transmissionmethodandnetworkprotocol,etc.Itsbasicfunctionsare:①Linecontrol:controltheonandoffofcommunicationlines,theinterfaceoflineterminationequipment(suchasmodems),andmonitorlinestatus.②Terminalcontrol:terminalselection,connectionandrelease,codingconversion,etc.③Organizemultiplecommunications:Transmitthedatafromeachcommunicationlinetothecomputercorrectlyatthesametime;distributethedatafromthecomputertothecorrespondingcommunicationline.④Combinationanddecompositionofcharacters:theserialcodefromthecommunicationlineisassembledandcombinedintoaparallelcodeandsenttothecomputer;theparallelcodefromthecomputerisdecomposedintoaserialcodeandsenttothecommunicationline.⑤Transmissioncontrol:theimplementationofcommunicationprocedures,thatis,thedatalinklayerprotocolofthenetworknodefunction.Thisregulationstipulatestherulesfordatatransmissionbetweentwoadjacentnodesonasinglelink,includingdataencoding,synchronizationmode,informationformat,operationsteps,etc.⑥Adjustmentoftransmissionspeedanddatabuffering:Thedatatransmissionrateonthecommunicationlineisgenerallylowerthantheinputandoutputtransmissionrateofthecomputer.Whentherearemultiplecommunicationlines,itisnecessarytosetabuffertoadjustthespeed.⑦Textandtelegramprocessing:automaticnumbering,combinationandcollection,analysisandediting,exchangeofrecords,errordiagnosis,etc.oftextandtelegrams.⑧Errorhandling:Useeffectiveerrordetectionandcorrectionmethodstofindandcorrecterrorsthatoccuronthecommunicationline,anduseerrorrecoveryprocedures,re-executionandothermeasurestocontrolothererrors.

Perusrakenne

Keskusohjausosa

Itisthemainbodyoftheviestintäohjausprosessori.Thecharacteristicsoftheviestintäohjausprosessoriare:

①Intheinstructionsystem,the"register-register"typeinstructionsarethemajority,themainmemoryaccessinstructionsarereduced,themultiplicationandfloating-pointoperationsinstructionshavebeendeleted,andsomespecialinstructionshavebeenadded.,Suchascycliccodeerrorcorrectioninstructions.

②Therearemultiplesetsofgeneralregisters,whichcanmakeuptohundredsofcommunicationlinesworkatthesametime.Inthecaseoffrequentinterruptions,thecostofsavingandrestoringthescenecanbereduced,therebyincreasingthetotalnumberofacceptablelinesandprocessingcapacity.

③Themainmemory(mainmemory)hasalargecapacity.Theviestintäohjausprosessorigenerallydoesnothaveauxiliarymemory,andthecommunicationsoftwareisstoredinthemainmemory.

④Itisequippedwithabufferdevice,whichcanbedividedintotwotypes:bytebufferandtext/messagebuffer.Theformerinterruptstheprocessormoretimesandtheprogramburdenislarger,butthedevicecapacityissmall,andismostlyusedingeneralcommunicationcontrollers;thelatterexchangesinformationwiththehostcomputerintheunitoftextandtelegrams,andeachcommunicationlinehasalargerBuffer,thenumberofinterruptsisless,andtheefficiencyishigher.

Linecontrol osa

Includestwoparts:lineinterfacepartandcommoncontrolpart.

①Lineinterfacecomponent:itsfunctionistoperformlevelconversionandinterfaceoperations.Therearemanytypesoflinesandterminals,anditisusuallynecessarytodesignavarietyoflineinterfacecomponents,allowinguserstoselectaccordingtotheirneedswhenthesystemisformed.Thelowestlayerinthenetworkfunctionofthecomputernetwork,thephysicallayer,mainlyreferstotheinterfacebetweenthelinecomponentsandthemodem.Itisimplementedbyhardware.Thephysicallayerprotocolisthestandardagreementforthisinterface.Theinterfacestandardspecifiesthename,function,electricalcharacteristics,andmechanicalcharacteristicsoftheinterfacelinesbetweendataterminalequipment.

②Commoncontrolcomponent:itsfunctionistocontrolthecombinationanddecompositionofcharactersandthescanningandsamplingoflineinterfacecomponents.Eachcircuithasacorrespondingstorageunitinthememory,butsharesasetofhardwarecontrolcircuits.Thelatterscanseachstorageunit;whenacertainunitisscanned,thecorrespondingcommunicationlineoccupiesthehardwarecontrolcircuitforcharactercombinationanddecomposition.Eachlinecanusethehardwarecontrolcircuitintime-sharingmode,andthestorageunitstoresthesceneofthelastoperationofthecorrespondingline

tietokoneen käyttöliittymän ohjausosa

andthecontrollerequippedwithinput-outputdeviceThecomputerinterfaceisthesame.

ClassificationTheviestintäohjausprosessoriisdividedintofivetypesaccordingtothefunctionofthecomputernetworknode:communicationinterface,communicationcontroller,front-endprocessor,terminalprocessorandnodeprocessor.

CommunicationinterfaceItonlyhasthelinecontrolpartinthebasicstructure,whichcompletesthelinecontrolandmulti-channelcontrolinthebasicfunction.Itscharacteristicisthatitisbit-basedSend,receiveandbuffercharactersortextmessages.

CommunicationControllerIthasthreepartsofthebasicstructure,andhasotherbasicfunctionsbesidesthetransmissionandprocessingfunctions.Itischaracterizedbysendingandreceiving,bufferingandprocessingtextmessagesaccordingtocharactersor"frames"or"packets".

Front-endprocessorIthasstrongtransmissioncontrolandtextprocessingcapabilities.Itscharacteristicistosendandreceive,bufferandprocessinunitsofmessagesandtelegrams.Itiscomposedofsmallcomputers.Whenthecommunicationcontrolmodeischanged,itisnotnecessarytochangethewiringbetweenthemachinesbutonlyneedtomodifythehardwareandsoftwareslightly,soithasgreaterflexibilityandeconomy.

TerminalProcessorWhentheuserterminaldoesnothavealocalhostcomputeravailableorthelocalhostcomputerdoesnothaveatime-sharingsystem,itallowstheuserterminaltoenterThecomputernetworkenjoyscomputerresources.Ithasastrongterminalcontrolfunction.

NodeprocessorItcanstrengthenthetransmissioncontrolfunctioninthebasicfunction,connectthecommunicationlinesinthecomputernetworktoeachother,andrealizetheconversionofdataformatandcommunicationprocedures.Itscharacteristicisthatitisnotdirectlyconnectedtothehostcomputeroruserterminal.

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