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.VHDLhasmanyfeaturesappropriatefordescribingthebehaviorofelectroniccomponentsrangingfromsimplelogicgatest

2、ocompletemicroprocessorsandcustomchips.FeaturesofVHDLallowelectricalaspectsofcircuitbehavior(suchasriseandfalltimesofsignals,delaysthroughgates,andfunctionaloperation)tobepreciselydescribed.TheresultingVHDLsimulationmodelscanthenbeusedasbuildingblocksinlargercircuits(usingschematics,blockdiagrams

3、orsystem-levelVHDLdescriptions)forthepurposeofsimulation. VHDLisalsoageneral-purposeprogramminglanguage:justashigh-levelprogramminglanguagesallowcomplexdesignconceptstobeexpressedascomputerprograms,VHDLallowsthebehaviorofcomplexelectroniccircuitstobecapturedintoadesignsystemforautomaticcircuitsyn

4、thesisorforsystemsimulation.LikePascal,CandC++,VHDLincludesfeaturesusefulforstructureddesigntechniques,andoffersarichsetofcontrolanddatarepresentationfeatures.Unliketheseotherprogramminglanguages,VHDLprovidesfeaturesallowingconcurrenteventstobedescribed.Thisisimportantbecausethehardwaredescribedu

5、singVHDLisinherentlyconcurrentinitsoperation.OneofthemostimportantapplicationsofVHDListocapturetheperformancespecificationforacircuit,intheformofwhatiscommonlyreferredtoasatestbench.TestbenchesareVHDLdescriptionsofcircuitstimuliandcorrespondingexpectedoutputsthatverifythebehaviorofacircuitovertim

6、e.TestbenchesshouldbeanintegralpartofanyVHDLprojectandshouldbecreatedintandemwithotherdescriptionsofthecircuit. AstandardlanguageOneofthemostcompellingreasonsforyoutobecomeexperiencedwithandknowledgeableinVHDLisitsadoptionasastandardintheelectronicdesigncommunity.UsingastandardlanguagesuchasVHDLv

7、irtuallyguaranteesthatyouwillnothavetothrowawayandrecapturedesignconceptssimplybecausethedesignentrymethodyouhavechosenisnotsupportedinanewergenerationofdesigntools.Usingastandardlanguagealsomeansthatyouaremorelikelyto