network cards for the pandora multimedia systemnew

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1、NetworkCardsforthePandoraMultimediaSystemDJClarke,OlivettiResearchLimitedGJStark,AdvancedTelecommunicationModulesLtdORLTechnicalReport94-5Contents1Introduction11.1ThePandoraSystem:::::::::::::::::::::::::::11.2ThePandoraNetworkCards::::::::::::::::::

2、::::21.3TheFirmware:::::::::::::::::::::::::::::::22HardwareOverview32.1CambridgeFastRingChipset::::::::::::::::::::::32.2Technology::::::::::::::::::::::::::::::::32.3CircuitDesign::::::::::::::::::::::::::::::43SoftwareOverview83.1DivisionofLabour:

3、:::::::::::::::::::::::::::83.2Slaveprocessorsoftware:::::::::::::::::::::::::83.3Masterprocessorsoftware::::::::::::::::::::::::94Conclusion131Introduction1.1ThePandoraSystemIn1990OlivettiResearchLimitedinCambridgebegantodeployanetworkofMul-timediaw

4、orkstationsknownasPandora.EachWorkstationconsistedofacomputerrunningUnix(anARM-basedmachinefromAcornComputer)andanadd-onbox(the`PandoraBox')tohandlevideoandaudiotrac.Thevideoandaudiowascarriedonthelocal50Mbit/snetwork,theCambridgeFastRing(CFR)[3].Th

5、isremarkableset-upallowedmultiplestreamsofvideoandaudiotobesentconcur-rentlybetweentheworkstationsand,later,aleservermachineaswell.Thewholewasintegratedsothatausercouldmanipulatethevideoandaudiousingfamiliar-lookingX-Windowstools,withthevideoappeari

6、nginoneormorewindowsontheWorkstationscreen.[6][7]1ThePandoraBoxisaMIMD(MultipleInstructionMultipleData)multiprocessorimplementedusingInmosTransputers.[11]ThearchitectureoftheBoxisoutlinedbelowingure1.Figure1:ArchitectureofaPandoraBoxTheInmosTransput

7、erhashigh-speedseriallinksbuilt-in.InPandorathisfeatureisusedtopasscontrolmessagesanddatabetweenprocessors.TherearealsosomeextradatapathsintheformofFIFObuerstohandlevideotrac.TheearliestimplementationofthePandoraBoxdidnothaveaseparateNetworkInterfa

8、ce.TheServerTransputerwasusedtoconnecttheothersubsystemstogetherandalsotohandletheCambridgeFastRing(CFR)directly.ItwasclearthattheServerwastherstprocessortosaturatewhentheBoxwasheavilyloaded;thesolutionwastodesignanewcardtohandlethenetwork.Thiswould