chap01-a_systems_engineering_approach

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1、CHAPTER1ASystemsEngineeringApproachtoEmbeddedSystemsDesignInThisChapterÑDefineembeddedsystemÑIntroducethedesignprocessÑDefineanembeddedsystemsarchitectureÑDiscusstheimpactofarchitectureÑSummarizetheremainingsectionsofthebook1.1WhatIsanEmbeddedSystem?

2、Anembeddedsystemisanappliedcomputersystem,asdistinguishedfromothertypesofcom-putersystemssuchaspersonalcomputers(PCs)orsupercomputers.However,youwillfindthatthedefinitionof“embeddedsystem”isfluidanddifficulttopindown,asitconstantlyevolveswithadvancesintechn

3、ologyanddramaticdecreasesinthecostofimplementingvari-oushardwareandsoftwarecomponents.Inrecentyears,thefieldhasoutgrownmanyofitstraditionaldescriptions.Becausethereaderwilllikelyencountersomeofthesedescriptionsanddefinitions,itisimportanttounderstandthere

4、asoningbehindthemandwhytheymayormaynotbeaccuratetoday,andtobeabletodiscussthemknowledgeably.Followingareafewofthemorecommondescriptionsofanembeddedsystem:îEmbeddedsystemsaremorelimitedinhardwareand/orsoftwarefunctionalitythanapersonalcomputer(PC).Thish

5、oldstrueforasignificantsubsetoftheembed-dedsystemsfamilyofcomputersystems.Intermsofhardwarelimitations,thiscanmeanlimitationsinprocessingperformance,powerconsumption,memory,hardwarefunctionality,andsoforth.Insoftware,thistypicallymeanslimitationsrelative

6、toaPC—fewerapplications,scaled-downapplications,nooperatingsystem(OS)oralimitedOS,orlessabstraction-levelcode.However,thisdefinitionisonlypartiallytruetodayasboardsandsoftwaretypicallyfoundinPCsofpastandpresenthavebeenrepackagedintomorecomplexembeddedsys

7、temdesigns.îAnembeddedsystemisdesignedtoperformadedicatedfunction.Mostembeddeddevicesareprimarilydesignedforonespecificfunction.However,wenowseedevicessuchaspersonaldataassistant(PDA)/cellphonehybrids,whichareembed-dedsystemsdesignedtobeabletodoavariety

8、ofprimaryfunctions.Also,thelatestdigitalTVsincludeinteractiveapplicationsthatperformawidevarietyofgeneral5Chapter1functionsunrelatedtothe“TV”functionbutjustasimportant,suchase-mail,webbrowsing,andgames.îAnembeddedsystemisacomput