电子信息科学专业英语En-unit2

电子信息科学专业英语Unit2ElectronicDesignAutomation2-1IntroductiontoconfigurablecomputingKeywordsTranslationExercisesNotesReadingKeywordsASIC(Application-SpecificIntegratedCircuit)专用集成电路encryption编密码，密码学frame帧FPGA(Field-ProgrammableGateArray)现场可编程门阵列versatility多功用性,通用性swap交换generality通用性patternrecognition模式识别imageprocessing图像处理Otherwordsautomation自动化操作binaryformat二进制格式precisely精确的，明确的amortize分期，分解structurally在结构上coarsegrained粗结构finegrained细结构fromscratch从无到有，白手起家tentative尝试性的ElectronicDesignAutomation电子设计自动化Octal八进制的Decimal十进制的Hexadecimal十六进制的TranslationComputersthatmodifytheirhardwarecircuitsastheyoperateareopeninganeweraincomputerdesign.Becausetheycanfilterdatarapidly,theyexcelatpatternrecognition,imageprocessingandencryption.可以在运行中改变自己的硬件电路的计算机在计算机设计领域正开辟一个新时代，因为它们可以快速地“过滤”数据，善长执行模式识别、图象处理和加密这类工作。Computerdesignersfaceaconstantstruggletofindtherightbalancebetweenspeedandgenerality.计算机设计者始终面临着寻找速度和通用性两者平衡的斗争。Theycanbuildversatilechipsthatperformmanydifferentfunctionsrelativelyslowly,ortheycandeviseapplication-specificchipsthatdoonlyalimitedsetoftasksbutdothemmuchmorequickly.他们可以设计出实现多种不同功能但速度相对较慢的通用芯片，或者设计出只能完成有限的任务而速度较快的专用芯片。Microprocessors(suchastheIntelPentiumorMotorolaPowerPCchipscommonlyfoundinpersonalcomputers)aregeneralpurpose:programminginstructionsencodedinbinaryformatcanleadamicroprocessorthroughvirtuallyanylogicalormathematicaloperationaprogrammercanconceive.[1]像常用于个人电脑的英特尔奔腾（IntelPentium）芯片和摩托罗拉PowerPC这些芯片，都是通用微处理器芯片:使用二进制格式编码的程序指令，可真正实现程序员所设计的任何逻辑和数学的运算。TheIntelPentium,forexample,wasneverdesignedspecificallytoexecuteeitherMicrosoftWordorthecomputergameDOOM,butitcanrunboth.比如，英特尔奔腾芯片永远不会指定专门用于Word文档处理或DOOM游戏的运行，二者可以一起在该芯片上运行。Incontrast,customhardwarecircuits,oftenknownasapplication-specificintegratedcircuits(ASICs),providepreciselythefunctionalityneededforaspecifictask.相对比，客户定制的硬件电路，常称为专用集成电路ASIC，可为特定任务准确的提供所需要的功能。BycarefullytuningeachASICtoagivenjob,thecomputerdesignercanproduceasmaller,cheaper,fasterchipthatconsumeslesspowerthanaprogrammableprocessor.[2]通过为给定任务仔细调整每个ASIC电路，计算机设计者可以制造出更小、更便宜、速度更快且比可编程处理器功耗更少的芯片。AcustomgraphicschipforaPC,forinstance,candrawlinesorpaintpicturesonthescreen10or100timesasquicklyasageneral-purposecentralprocessingunitcan.比如，专用的PC机图形处理芯片能以通用CPU10倍到100倍的处理速度在屏幕上划线和绘图。定制的，用户化Asdesignersmaketheirchoicesbetweenversatilityandspeed,theymustalsoconfronttheissueofcost.设计者在对多功能性和速度二者做出选择时，也必须考虑芯片的造价问题。Awell-designedASICwillsolvethespecificproblemforwhichitwasdesigned,butprobablynotaslightlymodifiedproblemintroducedaftertheASICdesignisfinished.一个设计好的AISC，将可以解决事先设计好的指定问题，而解决不了在设计完成之后所引入的即使只被轻微改动的问题。Furthermore,evenifamodifiedASICcanbedevelopedforthenewproblem,theoriginalhardwarecircuitsmaybetoohighlycustomizedtobereusedinsuccessivegenerations.进一步说，即使一个修改过的AISC可以解决新的任务，但由于原有硬件电路过于专用化以至不可能在换代产品中再继续使用。Asaresult,theengineeringeffortrequiredtodesignandbuildanASICmustbeamortizedoverarelativelysmallnumberofunits.因此，设计和制造一个AISC的工程问题必须考虑将其分解成几个单元来进行。Anewdevelopmentinintegratedcircuitsoffersathirdoption:large,fast,field-programmablegatearrays,orFPGAs—highlytunedhardwarecircuitsthatcanbemodifiedatalmostanypointduringuse.集成电路的新发展提供了第三种选择：大规模、快速、现场可编程门阵列，或叫FPGA，即在使用中几乎可对电路中任何一点修改的、高度可调的硬件电路。FPGAsconsistofarraysofconfigurablelogicblocksthatimplementthelogicalfunctionsofgates.FPGA电路是由能实现门电路逻辑功能的可配置逻辑块阵列构成。Logicgatesarelikeswitcheswithmultipleinputsandasingleoutput.TheyareusedindigitalcircuitstoperformbasicbinaryoperationssuchasAND,NAND,OR,NORandXOR;逻辑门就像多个输入和单个输出的一些开关一样，它们在数字电路中可实现像与、与非、或、或非和异或这样的基本二进制运算操作。ExclusiveORNotORInmosthardwarethatisusedincomputingtoday,thelogicalfunctionsofgatesarefixedandcannotbemodified.目前在计算领域所采用的大多数硬件中，门电路的逻辑功能是固定不变、不能被修改的。InFPGAs,however,boththelogicfunctionsperformedwithinthelogicblocksandtheconnectionsbetweentheblockscanbealteredbysendingsignalstothechip.然而，在FPGA中，逻辑块内实现的逻辑功能和逻辑块间的连接都可以通过向芯片发送信号加以修改。TheseblocksarestructurallysimilartothegatearraysusedinsomeASICs,butwhereasstandardgatearraysareconfiguredduringmanufacture,theconfigurablelogicblocksinFPGAscanberewiredandreprogrammedrepeatedly,longaftertheintegratedcircuithasleftthefactory.[3]在结构上，这些逻辑块与某些AISC的门阵列是类似的，但标准的门阵列是在生产时配置好的，而FPGA中的可配置逻辑块可以在集成电路出厂后很长时间内反复重新布线和重新编程。ThekeythathasopenedthedoortoconfigurablecomputingisthedesignofnewFPGAsthatcanbeconfiguredextremelyquickly.开启可配置计算大门的关键技术是，新型的、能够配置得非常快的FPGA设计。Theearliestfield-programmablearraysrequiredseveralsecondsormoretochangetheirconnections—perfectlysuitableforengineerswhowantedtotestalternativecircuitdesignsorforcompaniesthatsolddevicesthatmightneedoccasionalupgrading.最早的FPGA需要几秒或更多的时间来改变它们的连接，这对于那些测试比较电路设计的工程师或对那些需要售后设备升级改进的公司来说是非常适合的。NewerFPGAscanbeconfiguredinonemillisecond,andweexpecttoseedeviceswithconfigurationtimesaslowas100microsecondswithintwoyears.新型的FPGA能在一毫秒之内配置完电路，而且我们有望在两年内能看到可以在100微秒内配置完成的器件。Ultimately,computingdevicesmaybeabletoadapttheirhardwarealmostcontinuouslyinresponsetochangesintheinputdataorprocessingenvironment.最终，计算设备几乎可以连续不断地调节它的硬件，以响应输入数据或处理环境的变化。TherearemanyvariationsonFPGAdesign,butthebasicstructureconsistsofalargenumberofconfigurablel