Wiley Real-Time Systems Design and
1、REAL-TIMESYSTEMSDESIGNANDANALYSISTHIRDEDITIONPhillipA.Lapla nteAJOHNWILEYasmblers,whichtranslatetheasmblylanguagein toaspecialbinaryformatcalledobjectormachinecode;andlinkers, whichpreparetheobjectcodeforexe-cution.Anoperatingsystemisa specializedcollectionofsystemprogramsthatmanaget
云南的景点2、hephysicalresourcesofthecomputer.Assuch,areal-timeoperating systemisasystemsprogram.Applicationprogramsareprogramswritt entosolvespecificproblems,suchaspayrollpreparation,inventor y,andnavigation.Certaindesignconsiderationsplayaroleinthede signofcertainsystemsprogramsandapplicationsoftwa
大料是什么3、reintendedtoruninreal-timeenvironments.Thenotionofa“system ”iscentraltosoftwareengineering,andindeedtoallengineering, andwarrantsformalization.Definition:Asystemisamappingofat ofinputsintoatofoutputs.Whentheinternaldetailsofthesystem arenotofinterest,themappingfunctioncanbeconsidered红花对女人的危害>视觉感受器
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4、asablackboxwithoneormoreinputnteringandoneormoreoutputx itingthesystem(eFigure1.1).Everyreal-worldentity,whethers
yntheticoroccurringnaturally,canbemod-eledasasystem.Incompu tingsystems,theinputsreprentdigitaldatafromI1I2InO1O2OmCo mputerSystemFigure1.1Asystemwithninputsandmoutpu
5、ts.1.1TERMINOLOGY3hardwaredevicesandothersoftwaresystems.Th einputsareoftenassociatedwithnsors,cameras,andotherdevice sthatprovideanaloginputs,whichareconvertedtodigitaldata,orp rovidedirectdigitalinput.Thedigitaloutputofthecomputersyste mcanbeconvertedtoanalogoutputstocontrolexternalh
6、ardwaredevicessuchasactuatorsanddisplays(Figure1.2).Modelin gareal-timesystem,asinFigure1.2,issomewhatdifferentfromthem oretraditionalmodelofthereal-timesystemasaquenceofjobstob escheduledandperformancetobepredicted,whichisverysimilartot hatshowninFigure1.3.Thelatterviewissimplisticint
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经典童谣100首7、hatitignoresthefactthattheinputsourcesandhardwareundercontr olarecomplex.Moreover,thereareo
边缘性性行为ther,sweepingsoftwareenginee ringconsiderationsthatarehiddenbythemodelshowninFigure1.3.C omputerSystemSensor1Sensor2SensornDisplayDataControlSignal1 ControlSignal2ControlSignalnCameraInputFigure1.2
8、
Typicalreal-timecontrolsystemincludinginputsfromnsorsandi magingdevicesandproducingcontrolsignalsanddisplayinformatio n[Laplante03b].ComputerSystemJob1Job2JobnScheduleFigure1.3A classicreprentationofareal-timesystemasaquenceofjobstob escheduled.41BASICREAL-TIMECONCEPTSLookagainatto
9、themodelofareal-timesystemshowninFigure1.2.Notethatinitsrea lizationthereissomedelaybetweenprentationoftheinputs(stim ulus)andappearanceoftheoutputs(respon).Thisfactcanbeforma lizedasfollows:Definition:Thetimebetweentheprentationofas etofinputstoasys
