外文翻译---语言概观

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1、附录4英文资料及译文1英文资料(FromDIGITALDESIGNprinciples&practices,JohnF.Wakerly)LanguageOverviewWhatisVHDL?VHDLisaprogramminglanguagethathasbeendesignedandoptimizedfordescribingthebehaviorofdigitalsystems.VHDLhasmanyfeaturesappropriatefordescribingthebehaviorofelectroniccomponentsrangingfromsimplelogicgates

2、tocompletemicroprocessorsandcustomchips.FeaturesofVHDLallowelectricalaspectsofcircuitbehavior(suchasriseandfalltimesofsignals,delaysthroughgates,andfunctionaloperation)tobepreciselydescribed.TheresultingVHDLsimulationmodelscanthenbeusedasbuildingblocksinlargercircuits(usingschematics,blockdiagra

3、msorsystem-levelVHDLdescriptions)forthepurposeofsimulation. VHDLisalsoageneral-purposeprogramminglanguage:justashigh-levelprogramminglanguagesallowcomplexdesignconceptstobeexpressedascomputerprograms,VHDLallowsthebehaviorofcomplexelectroniccircuitstobecapturedintoadesignsystemforautomaticcircuit

4、synthesisorforsystemsimulation.LikePascal,CandC++,VHDLincludesfeaturesusefulforstructureddesigntechniques,andoffersarichsetofcontrolanddatarepresentationfeatures.Unliketheseotherprogramminglanguages,VHDLprovidesfeaturesallowingconcurrenteventstobedescribed.Thisisimportantbecausethehardwaredescri

5、bedusingVHDLisinherentlyconcurrentinitsoperation.OneofthemostimportantapplicationsofVHDListocapturetheperformancespecificationforacircuit,intheformofwhatiscommonlyreferredtoasatestbench.TestbenchesareVHDLdescriptionsofcircuitstimuliandcorrespondingexpectedoutputsthatverifythebehaviorofacircuitov

6、ertime.TestbenchesshouldbeanintegralpartofanyVHDLprojectandshouldbecreatedintandemwithotherdescriptionsofthecircuit. AstandardlanguageOneofthemostcompellingreasonsforyoutobecomeexperiencedwithandknowledgeableinVHDLisitsadoptionasastandardintheelectronicdesigncommunity.Usingastandardlanguagesucha

7、sVHDLvirtuallyguaranteesthatyouwillnothavetothrowawayandrecapturedesignconceptssimplybecausethedesignentrymethodyouhavechosenisnotsupportedinanewergenerationofdesigntools.Usingastandardlanguagealsomeansthatyouaremorelikelyto