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1、姓名信息与通信学院2008-09.2课程名称专业英语学号一(每小题2分)选择题：阅读下列短文并在后边的问题下面的4个答案选择一个最合适的口禾OAnIntroductiontoFPGAConfigurableComputingComputerdesignersfaceaconstantstruggletofindthefightbalancebetweenspeedandgenerality.Theycanbuildversatilechipsthatperformmanydifferentfunctionsrela
2、tivelyslowly,ortheycandeviseapplication-specificchipsthatdoonlyalimitedsetoftasksbutdothemmuchmorequickly.Incontrast,customhardwarecircuits,oftenknownasapplication-specificintegratedcircuits(ASICs),providepreciselythefunctionalityneededforaspecifictask.Bycaref
3、ullytuningeachASICtoagivenjob,thecomputerdesignercanproduceasmaller,cheaper,fasterchipthatconsumeslesspowerthanaprogrammableprocessor.AcustomgraphicschipforaPC,forinstanee,candrawlinesorpaintpicturesonthescreen10or100timesasquicklyasageneral-purposecentralproc
4、essingunitcan.Asdesignersmaketheirchoicesbetweenversatilityandspeed,theymustalsoconfronttheissueofcost.Awell-designedASICwillsolvethespecificproblemforwhichitwasdesigned,butprobablynotaslightlymodifiedproblemintroducedaftertheASICdesignisfinished.Asaresult,the
5、engineeringeffort-requiredtodesignandbuildanASICmustbeamortized(刁卜抓隹)overarelativelysmallnumberofunits・ProgrammableCircuitryAnewdevelopmentinintegratedcircuitsoffersathirdoption:large,fast,field-programmablegatearrays,orFPGAs-highlytunedhardwarecircuitsthatcan
6、bemodifiedatalmostanypointduringuse.FPGAsconsistofarraysofconfigurablelogicblocksthatimplementthelogicalfunctionsofgates,whicharefixedandcannotbemodified・InFPGAs,however,boththelogicfunctionsperformedwithinthelogicblocksandtheconnectionsbetweentheblockscanbeal
7、teredbysendingsignalstothechip.TheseblocksarestructurallysimilartothegatearraysusedinsomeASICs,buttheconfigurablelogicblocksinFPGAscanberewiredandreprogrammedrepeatedly,longaftertheintegratedcircuithasleftthefactory.ApplicationsFPGAsplayboththerolesasthesystem
8、sintheirownrightandasprototypesforASICdesigns.CompletesystemdesignscanbeimplementedonasingleFPGAdevice・Thenumberofgatesandfeatureshasincreaseddramaticallytocompetewithcapabilitiest
