电气及自动化专业 外文翻译 13.docx

电气及自动化专业 外文翻译 13.docx

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电气及自动化专业外文翻译13

中国地质大学长城学院

本科毕业论文外文资料翻译

学院

工程技术学院

学生姓名

齐业亮

专业

电气工程及其自动化

学号

043130215

2017年3月10日

UsingLinuxinEmbeddedSystems

UNIXevokesawiderangeofemotions:

lovedbysomeforitspowerandflexibility,despisedbyothersforitseomplexandarcanecommands.UNIXhasestablishedacheckeredreputationintheworldofcomputing.

EASEOFUSE

UNIXisinfamousforitsglutofarcane,non-mnemonic,andcryptickeyboardcommands,eachwithmanycommand-lineswitches,whichcanbeincrediblyconfusingtoremember.ItsSVR4implementationcontainsmorethan2,000comands.Manyofthesefunctionscanbecombined,usingpipesandredirection.ThisillustratesoneofUNIX’sdesignfundamentals:

thecreationofalargeassortmentofveryspecializedandmodularcommandsthatcanbecombinedtoaccomplishcomplextasks.

WhileUNIXwasessentiallylimitedtousebysoftwareprofessionalsatuniversitiesandinapplicationsdevelopmenthouses,itscomplexcommand-linesyntaxandresultingflexibilitywereconsideredanadvantageratherthanaproblem.ButthissameflexibilityalsocreatesamajordrawbackforusingUNIXinabusiness-orientedmarket—themoreflexibleasystemis,themoredifficultitbecomestolearnandoperate.

UNIX’sscriptlanguagesprovideoneformofhelp.Usingscripts,asystemadministratorcantailorthesystemtoasetofusers’needsquickly.

AnotherfactormitigatingthedifficultiesofUNIX’sarcanecommandlanguagearetheGraphicUserInterfaces（GUIs）,suchasMotif,SunView,orOpenLook.GUIs,however,placeanotherlevelofincompatibilityproblemsonwhatisalreadyacomplexsystem.

Motifhasbeenportedtothemostdifferentarchitecturesand（becauseitfollowsthePresentationManagerstyle）isperhapsclosestinlookandfeeltoaPCinterfacesuchasMicrosoftWindows.SunViewisalsodominantbecauseofitslargeinstalledbaseandthenumbersofapplicationsprogrammerswhohavebecomefamiliarwithwritingsoftwaretoitsspecifications.

BINARYCOMPATIBILITY

UNIXmarketershavelookedwithsomeenvyatthehuge-baseofshrink-wrappedapplicationsavailableintheDOSworldandhavepromisedthatbinary-compatibleapplicationsforsystemsisjustaroundthecorner.Thesepromiseshaveyettobemetinanysignificantway.Whilebinarycompatibilityisnotyetavailable,itisgettingeasiertosharedataandapplicationsacrossdifferentmachines.

PORTABILITY

Comparedwithmostoperatingsystemsources,UNIXcodeisquitemoveUNIXtodifferentarchitectures.ButaUNIXporttoanewsystemisnotatrivialmatter,offentakingseveralman-yearsofwork,andcanresultinglitchesandmalfunctions,whichmaycreateverysubtleinconsistenciesinperformance.Thesebugsareoftendifficulttoidentifyandcorrect.

Havingthesourcecodeavailableforyourcomputer’soperatingsystemisbeneficialanddetrimental:

iftheOSlackscertaindesirablefeatuers,havingthesourcesin-housegreatlyenhancesacompany’sabilitytomakenecessarychanges.

Ontheotherhand,thecustomizedversionoftheoperatingsystem,withitsnewormodifiedfeaturesmaylaterpresentcompatibilityproblemswithnewerreleasesorpurchasedapplication.

WhyLinux?

Intelligentdedicatedsystemsandapplicancesusedininterface,monitoring,communications,andcontrolapplicationsincreasinglydemandtheservicesofasophisticated,state-of-the-artoperatingsystems.Manysuchsystemsrequireadvancedcapabilitieslike:

highresolutionanduser-friendlygraphicaluserinterfaces（GUIs）;TCP/IPconnectivity;substitutionofreliable（andlowpower）flashmemorysolidstatediskforconventionaldiskdrives;supportfor32-bitultra-high-speedCPUs;theuseoflargememoryarrays;andseeminglyinfinitecapacitystoragedevicesincludingCD-ROMsandharddisks.

Thisisnotthestuffofyesteryear’s“standalone”code,“roll-your-own”kernels,or“plainoldDOS”,No,thosedaysaregone—forever.

Thentoo,considertherapidlyacceleratingpaceofhardwareandchipsetinnovation—accompaniedbyextremelyrapidobsolescenceoftheolderdevices.Combinethesetwo,andyoucanseewhyit’sbecomeanenormouschallengeforcommercialRTOSvendorstokeepupwiththeconstantchurningofhardwaredevices.Supportingthenewestdevicesinatimelymanner—evenjusttostayclearoftheunrelentingsteamrollerofchipsetobsolescence–takesalargeandconstantresourcecommitment.Ifit’sastruggleforthecommercialRTOSvendorstokeepup,goingitalonebywritingstandalonecodeoraroll-your-ownkernelcertainlymakesnosense.

Withtheoptionsnarrowing,embeddedsystemdevelopersfindthemselvesfacedwithadilemma:

Ontheonehand,today’shighlysophisticatedandempoweredintelligentembeddedsystems—basedonthenewestchipsandhardwarecapabilities—demandnotinglessthanthepower,sophistication,andcurrencyofsupportprovid