Microprocessor - Wikipedia,thefreeencyclopedia Page 1of 16 Microprocessor From Wikipedia,the free encyclopedia A microprocessor incorporatesthefunctionsof acomputer's central processingunit(CPU)onasingle integratedcircuit,[1] (IC)oratmostafewintegratedcircuits. [2]Itisa multipurpose,programmabledevicethataccepts digitaldata asinput,processesitaccordingtoinstructionsstoredinits memory,andprovidesresultsasoutput.Itisanexampleof sequentialdigitallogic,asithasinternalmemory. Microprocessorsoperateonnumbersandsymbols representedin the binarynumeralsystem. Theadventoflow-costcomputersonintegratedcircuitshas transformedmodernsociety.General-purpose microprocessorsinpersonalcomputersareusedfor computation,textediting,multimediadisplay,and Intel 4004,thefirstgeneral-purpose, communicationovertheInternet.Manymore commercial microprocessor microprocessorsare partof embeddedsystems,providing digitalcontrolofamyriadofobjectsfromappliancesto automobilestocellular phonesandindustrial processcontrol. Contents ■ 1Origins ■ 2Embeddedapplications ■ 3Structure ■ 4Firsts ■ 4.1Intel4004 ■ 4.2TMS1000 ■ 4.3Pico/GeneralInstrument ■ 4.4CADC ■ 4.5GilbertHyatt ■ 4.6Four-PhaseSystemsAL1 ■ 58bitdesigns ■ 612bitdesigns ■ 716bitdesigns ■ 832bitdesigns ■ 964bitdesignsinpersonalcomputers ■ 10Multicoredesigns ■ 11RISC ■ 12Special-purposedesigns ■ 13Marketstatistics ■ 14See also ■ 15Notes ■ 16References ■ 17Externallinks http://en.wikipedia.org/wiki/Microprocessor 2012 -03 -01 Microprocessor -Wikipedia,thefreeencyclopedia Page 2of 16 Origins Duringthe1960s,computer processorswereconstructedoutofsmallandmedium-scaleICseach containingfromtenstoa fewhundredtransistors.Foreachcomputer built,allofthesehadtobe placedandsolderedontoprintedcircuit boards,andoftenmultiple boardswouldhavetobe interconnectedinachassis.Thelargenumberofdiscretelogicgatesusedmoreelectrical power— andtherefore,producedmoreheat—thanamoreintegrateddesignwithfewerICs.Thedistancethat signalshadtotravel betweenICsonthe boardslimitedthespeedatwhichacomputercouldoperate. Inthe NASAApollospacemissionstothe mooninthe1960sand1970s,allonboardcomputations for primaryguidance,navigationandcontrolwere providedbyasmallcustom processorcalled"The ApolloGuidanceComputer".Ituseda primitive gatearray whoseonlylogicelementswerethree- input NORgates.[3] TheintegrationofawholeCPUontoasinglechiporonafewchipsgreatlyreducedthecostof processingpower.Theintegratedcircuit processorwas producedinlargenumbers byhighly automatedprocesses,sounitcostwaslow.Single-chip processorsincreasereliabilityasthere were manyfewerelectricalconnectionstofail.Asmicroprocessordesignsgetfaster,thecostof manufacturingachip(withsmallercomponents builtonasemiconductorchipthesamesize) generallystaysthesame. Microprocessorsintegratedintooneorafewlarge-scaleICsthearchitecturesthathadpreviously beenimplementedusingmanymedium-andsmall-scaleintegratedcircuits.Continuedincreasesin microprocessorcapacityhaverenderedotherformsofcomputersalmostcompletelyobsolete(see historyofcomputinghardware),withoneormoremicroprocessorsusedineverythingfromthe smallest embeddedsystemsandhandhelddevicestothelargest mainframesandsupercomputers. Thefirstmicroprocessorsemergedintheearly1970sandwereusedforelectronic calculators,using binary-codeddecimal(BCD)arithmeticon4bit words.Other embeddedusesof4-bitand8bit microprocessors,suchas terminals,printers,variouskindsofautomationetc.,followedsoonafter. Affordable8bitmicroprocessorswith16-bitaddressingalsoledtothefirstgeneral-purpose microcomputersfromthemid-1970son. Sincetheearly1970s,theincreaseincapacityofmicroprocessorshasfollowedMoore'slaw;this originallysuggestedthatthenumberoftransistorsthatcanbefittedontoachipdoubleseveryyear, [4] thoughMoorelaterrefinedthe periodtotwoyears. [5] Embedded applications Thousandsofitemsthatweretraditionallynotcomputer-relatedincludemicroprocessors.These includelargeandsmallhouseholdappliances,cars(andtheiraccessoryequipmentunits),carkeys, toolsandtestinstruments,toys,lightswitches/dimmersandelectricalcircuit breakers,smokealarms, batterypacks,andhi-fiaudio/visualcomponents(from DVD playerstophonographturntables.) Suchproductsascellulartelephones,DVDvideosystemandATSCHDTV broadcastsystem fundamentallyrequire consumerdeviceswithpowerful,low-cost,microprocessors.Increasingly stringent pollutioncontrolstandardseffectivelyrequireautomobilemanufacturerstouse microprocessorenginemanagementsystems,toallowoptimalcontrolofemissionsoverwidely varyingoperatingconditionsofanautomobile.Non-programmablecontrolswouldrequirecomplex, bulky,orcostlyimplementationtoachievetheresults possiblewithamicroprocessor. Amicroprocessor control programcanbe easilytailoredtodifferentneedsofa productline, allowingupgradesinperformancewithminimalredesignofthe product.Differentfeaturescanbe implementedindifferentmodelsofa productlineatnegligible productioncost. http://en.wikipedia.org/wiki/Microprocessor 2012 -03 -01 Microprocessor -Wikipedia,thefreeencyclopedia Page 3of 16 Microprocessorcontrolofasystemcanprovidecontrolstrategiesthatwouldbeimpracticalto implementusingelectromechanicalcontrolsor purpose-builtelectroniccontrols.Forexample,an engine controlsysteminanautomobilecanadjustignitiontimingbasedonenginespeed,loadonthe engine,ambienttemperature,andanyobservedtendencyforknocking-allowinganautomobileto operateonarangeoffuelgrades. Structure Theinternalarrangementofamicroprocessorvaries dependingontheageofthedesignandtheintendedpurposes ofthe processor.Thecomplexityofanintegratedcircuitis boundedbyphysicallimitationsofthenumberoftransistors thatcanbe putontoonechip,thenumberof package terminationsthatcanconnectthe processortoother partsof thesystem,thenumberofinterconnectionsitis possibleto makeon thechip,andtheheatthatthechipcandissipate. Advancingtechnologymakesmorecomplexandpowerful chipsfeasibletomanufacture. A blockdiagramoftheinternal architectureoftheZ80 Aminimalhypotheticalmicroprocessormightonlyinclude microprocessor,showingthe anarithmeticlogicunit(ALU)andacontrollogicsection. arithmeticandlogic section,register TheALU performsoperationssuchasaddition,subtraction, file,control logicsection,andbuffers andoperationssuchasANDorOR.Eachoperationofthe toexternaladdressanddata lines ALUsetsoneormoreflagsinastatusregister,which indicatetheresultsofthelastoperation(zerovalue,negative number,overflow.orothers).Thelogicsectionretrievesinstructionoperationcodesfrommemory, andinitiateswhateversequenceofoperationsoftheALUrequiredtocarry outtheinstruction.A singleoperationcodemightaffectmanyindividualdata paths,registers,andotherelementsofthe processor. Asintegratedcircuittechnologyadvanced,itwasfeasibletomanufacturemoreandmorecomplex processorsonasinglechip.Thesizeofdataobjects becamelarger;allowingmoretransistorson a chipallowedwordsizestoincreasefrom4-and8-bitwordsuptotoday's64bitwords.Additional featureswereaddedtothe processorarchitecture;moreon-chipregistersspeededup programs,and complexinstructionscouldbeusedtomakemorecompact programs.Floatingpointarithmetic,for example,wasoftennotavailableon8bitmicroprocessors,buthadtobecarriedoutinsoftware. Integrationofthefloatingpointunitfirstasaseparateintegratedcircuitand thenas partofthesame microprocessorchip,speededupfloatingpointcalculations. Occasionallythe physicallimitationsofintegratedcircuitsmadesuchpracticesasa bitslice approachnecessary.Insteadof processingallofalongwordononeintegratedcircuit,multiple circuitsinparallel processedsubsetsofeachdataword.Whilethisrequiredextralogictohandle,for example,carryandoverflowwithineachslice,theresultwasasystemthatcouldhandle,say,32-bit wordsusingintegratedcircuitswithacapacityforonly4bitseach. Withtheabilitytoputlargenumbersoftransistorsononechip,it becomesfeasibletointegrate memoryonthesamedieasthe processor.ThisCPUcachehastheadvantageoffasteraccessthan off-chipmemory,andincreasesthe processingspeedofthesystemformanyapplications.Generally, processorspeedhasincreasedmorerapidlythanexternalmemoryspeed,socachememoryis necessaryifthe processorisnottobedelayedbyslowerexternalmemory. http://en.wikipedia.org/wiki/Microprocessor 2012 -03 -01 Microprocessor -Wikipedia,thefreeencyclopedia Page 4of 16 Firsts Three projectsdeliveredamicroprocessorataboutthesametime: GarrettAiResearch's CentralAir DataComputer(CADC)(1968),TexasInstruments(TI)TMS1000(1971September),andIntel's 4004(1971 November). Intel 4004 Main article: Intel 4004 The Intel4004isgenerallyregardedasthefirst commerciallyavailablemicroprocessor, [6][7]andcost $60. [8]Thefirstknownadvertisementforthe4004is datedNovember15,1971andappearedinElectronic The 4004 withcover removed(left)andas News.[9]The projectthat producedthe4004originated in1969,whenBusicom,aJapanesecalculator actuallyused(right) manufacturer,askedInteltobuildachipsetforhigh- performancedesktopcalculators.Busicom'soriginaldesigncalledfora programmablechipset consistingofsevendifferentchips.Threeofthechipsweretomakeaspecial-purposeCPUwithits programstoredinROManditsdatastoredinshiftregisterread-writememory.TedHoff,theIntel engineerassignedtoevaluatethe project,believedtheBusicomdesigncouldbesimplifiedbyusing dynamicRAMstoragefordata,ratherthanshiftregistermemory,andamoretraditionalgeneral- purposeCPUarchitecture.Hoffcameup withafour–chiparchitectural proposal:aROMchipfor storingthe programs,adynamicRAMchipforstoringdata,asimpleI/Odeviceanda4-bitcentral processingunit(CPU).Althoughnotachipdesigner,hefelttheCPUcouldbeintegratedintoa singlechip,butashelackedthetechnicalknow-howtheidearemainedjustawishforthetime being. WhilethearchitectureandspecificationsoftheMCS-4camefromtheinteractionofHoffwith StanleyMazor,asoftwareengineerreportingtohim,andwithBusicomengineer