l1-基本认识计算机学院专业基础课

内容主要取材于CS61C第1数制NumberBases(数的进制Signed(有符合vsUnsigned(无符号SignExtension(符合扩展航空航天大学计算机内容主要取材于CS61C第1数制NumberSignedvs.Sign航空航天大学计算机MainframeEra:1950s-EnablingTech:ComputersBigPlayers:“BigIron”(IBM,Cost:$1M,Target:UsingCOBOL,Fortrantimesharing(分时 Summer2012--Lecture puterEra:BigPlayers:Digital,Cost:$10k,Target:Labs&Using:C,UNIX Summer2012--Lecture PCEra:Mid1980s-MidBigPlayers:Apple,Cost:$1k,Target:Consumers Using:Basic,Java,Windows Summer2012--Lecture Post-PCEra:Late2000s-alMobileDevices(PMD):EnablingTech:Wirelessnetworking,BigPlayers:Apple,Nokia,Cost:$500,Target:ConsumersontheUsing:ObjectiveC,Android Summer2012--Lecture Post-PCEra:Late2000s-EnablingTech:LocalAreaNetworks,broadbandBigPlayers: ,Target:Transientusersoruserswhocannotaffordhigh-endequipment Summer2012--Lecture AdvancedRISCMachineinstructionsetinsideYouwilllearnhowtodesignandprogramarelatedRISCcomputer:MIPSinstructioninstructionset

YouwilllearnaboutMIPSprocessor,cache(高缓存MemoryI/Ointhis Summer2012--Lecture WhatisthiscourseItisaboutthehardware-softwareinterface(接口Whatdoestheprogrammerneedtoknowtoachievethehighestpossibleperformance(性能)?Uselow-levelprogramminglanguages(closertounderlyinghardware)Allowsustotalkaboutkeyhardwarefeaturesinhigher-leveltermsAllowsprogrammerstoharnessunderlyinghardwareparallelism(并行性)forhighperformance包括MIPSprocessor、memory、I/O Summer2012--Lecture energyefficentWhyNot80x86vs.energyefficentOncelearnone,easytopickup80x86instructionsetisnot≈FullsuitcasethenaddclothesonwaytoClasstimeprecious;whyspendonclient(PostPCera)vs.fastprocessorofdesktop(PCera)MIPSrepresentsmorepopularinstruction2010:6.1BARM,0.3B80x86(20XMachineApplication(ex:

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I/ODatapath&DigitalDigitalCircuitCircuitSixGreatIdeasComputerMoore’sPrincipleofLocality/MemoryPerformanceMeasurement&Dependabilityvialayer/layer/层次locality/局部性memory 层次measurement/度GreatIdea#1:LevelsofProgram(e.g.Program(e.g.

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ords,colors,data,logic,(e.g.blockdiagrams)LogicCircuitDescription(CircuitSchematicDiagrams)representation/interpretation/解释schematicdiagram/原理representation/interpretation/解释schematicdiagram/原理Predicts:Predicts:Transistorperchipdoublesevery2years#of#oftransistorsonanintegratedcircuit B.S.Caltransistor/ Summer Lecture transistor/GreatIdea#3:PrincipleofLocality/MemoryHierarchydistancefromTrade-offinspeedandcostvs.capacity!virtualmemory/虚 器tradeoff/权衡(折衷GreatIdea#4: Summer2012--Lecture GreatIdea#5:MeasurementandAllowsdirectcomparisonsofarchitectures ficationofimprovementsItisallabouttimetofinishIncludesbothsetupandMatchapplicationandhardwaretoSpecialhardwarefeatures,likespecializedinstructions(e.g.matrixmanipulation)setup/建立locality/局部 Summersetup/建立locality/局部GeneAmdahlComputerPioneerPh.D.Wisconsin Summer2012--Lecture 内容主要取材于CS61C第1数制NumberSignedvs.Sign航空航天大学计算机NumberGreatIdea#1:LevelsofInsideacomputer,everythingstoredasasequenceof0’sand1’s(bits)Eventhisis HowdowerepresentnumbersinthisLet’sstartwith Summer2012--Lecture NumberKeyterminology:digit(d)andbaseValueofi-thdigitisd×Biwhereistartsat0andincreasesfromrighttoleftndigitnumberdn-1dn-2...value=dn-1Bn-1+dn-2Bn-2+...+d1B1+InbaseB,eachdigitisoneofBpossibleBaseisnotatedeitherasaprefixor Summer2012--Lecture CommonlyUsedNumber–Symbols:0,1,2,3,4,5,6,7,8,Notation:9472ten=Binary(baseSymbols:0,Notation:101011two=Symbols:0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,Notation:2A5Dhex= Summer2012--Lecture NumberBase3219472ten= + + + + + + + + +9472ten= + + +=0xA15=0b10100001 Summer2012--Lecture BitsCanRepresentndigitsinbaseBcanrepresentatmostBnEachofthendigitsisoneofBpossibleHavemorethings?AddmoreExample:Logicalvalues(1bit)–0isFalse,1isExample:26lettersrequire5bits(25=32>Example:Studentsinthisclass(?Forconvenience,cangroupintonibbles(4bits)bytes(8setup/建立locality/局部 Summersetup/建立locality/局部UnsignedRepresentnon-negative(unsigned)integersusingbase00000000000000000000000000000000two=00000000000000000000000000000001two=00000000000000000000000000000010two= 01111111111111111111111111111101two=01111111111111111111111111111110two=01111111111111111111111111111111two=10000000000000000000000000000000two=10000000000000000000000000000001two=10000000000000000000000000000010two= 11111111111111111111111111111101two=11111111111111111111111111111110two=11111111111111111111111111111111two= Summer2012--Lecture Numbersreallyhavedigits,buthardwarecanonlystoreafinitenumberofthem(fixed)UsuallyignoreleadingLeftmostismostsignificantbitRightmostisleastsignificantbitOverflowiswhentheresultofanarithmeticoperationcan’tberepresentedbythehardwarebits0b0000000001

mostsignificantbit/最高有效位overflow/arithmetic/mostsignificantbit/最高有效位overflow/arithmetic/SignedProgramsoftenneedtodealwithnegativenumbers,sohowdoweencodethese?nbitscanrepresent2ndifferentIdeally,wanttherangeevenlysplitbetweenpositiveandnegativeCanweencodetheminsuchawaythatwecanusethesamehardwareregardlessofwhetherthenumbersaresignedorunsigned? Summer2012--Lecture SignandMSBgivessign:0ispositive,1isnegative,restofbitstreatedasunsigned(magnitude)–Examples:0b10000010=-2,0b00000111=7Twozeros!0b00…0(+0)and0b10…0(-Cannotreuseunsigned Summer2012--Lecture Two’sMinormodificationofone’s–“Shift”representationofnegativenumbersdownbyonetoremoveduplicatezero10000...

00001These“shifted”by

numeralalwaysincrementstheintegerTonegate:complementthebitsandadd Summer2012--Lecture Sign

Two’s00000000000000000000000000000000two=00000000000000000000000000000001two=00000000000000000000000000000010two= 01111111111111111111111111111101two=01111111111111111111111111111110two=01111111111111111111111111111111two=10000000000000000000000000000000two=10000000000000000000000000000001two=10000000000000000000000000000010two= 11111111111111111111111111111101two=11111111111111111111111111111110two=11111111111111111111111111111111two= Summer2012--Lecture A A nn2i0)A2ii2A0(即an11A2n12ii假设[A]补由an-1an-2…a1a0表 an-10表示A为正an-11表示A为负［X］补与［－X］若[x]补则[x]x0x