电子科技大学期末数字电子技术考试题A卷参考答案

电子科技大学2010期末数字电子技术考试题A卷-参考答案电子科技大学二零零九至二零一零学年第二学期期末考试A年7月日0分一二三四五六七八九十得分一、Tofillyouranswersinthe（1’25）×1.If[X]=-110,thentwo's-complement=[],102[X]one's-complement=[].(Assumedthenumbersystemis8-bitlong)22.Performingthefollowingnumbersystemconversions:A.[10101100]=[0]24212B.[1625]=[01001]excess-310C.[1010011GRAY=[10011000]8421BCD(1，4，5，6)=3.IfF,thenF0，2，3，7).DA,B,CA,B,CA,B,C4.Iftheparametersof74LS-seriesaredefinedasfollows:Vmax=0.5Vmin=2.7OLOHVmax=0.8Vmin=2.0thenthelow-stateDCnoisemarginis0.3V,theILIHhigh-stateDCnoisemarginis0.7V5.Assigning0toLowand1toHighiscalledpositivelogic.ACMOSXORgateinpositivelogiciscalledXNORgateinnegativelogic..6.Asequentialcircuitwhoseoutputdependsonthestatealoneiscalledamachine.Moore7.Todesigna"001010"serialsequencegeneratorbyshiftregisters,theshiftregistershouldneed4bitasleast.8.Ifweusethesimpleststateassignmentmethodfor130sates,thenweneedatleast1/9电子科技大学2010期末数字电子技术考试题A卷-参考答案8statevariables.9.OnestatetransitionequationisQ*=JQ'+K'Q.IfweuseDflip-floptocompletetheequation,theDinputterminalofDflip-flopshouldbehavethefunctionD=JQ'+K'Q.10.WhichstateinFig.1isambiguousD11.ACMOScircuitisshownasFig.2,itslogicfunctionz=+ABFig.112.Ifnumber[A]two's-complement=01101010andone's-complement=1001,calculate[A-B]two's-complementandindicatewhetherornotoverflowoccurs.(Assumedthenumbersystemis8-bitlong)[A-B]two's-complement=01110000,overflowno13.IfaRAM’scapacityis16Kwords8bits,theaddressinputsshouldbe14bits;We×need8chipsof8K8bitsRAMtoforma16K32bitsROM..14.WhichistheXORgateofthefollowingcircuitA.15.Thereare2－ninvalidstatesinann-bitringcounterstatediagram.n16.AnunusedCMOSNORinputshouldbetiedtologicLowlevelor0.17.ThefunctionofaDACistranslatingtheoutputs.Digitalinputstothesamevalueofanalog二、CompletethefollowingtruthtableoftakingavotebyA,B,C,whenmorethantwoofA,B,Capprovearesolution,theresolutionispassed;atthesametime,theresolutioncan’tgothroughifAdon’tagree.ForA,B,C,assume1isindicatedapproval,0isindicatedopposition.FortheF,assume1ispassed,0isrejected.（5’）ABCF2/9电子科技大学2010期末数字电子技术考试题A卷-参考答案00001111001100110101010100000111三、ThecircuittothebelowrealizesacombinationalfunctionFoffourvariables.FillintheKarnaughmapofthelogicfunctionFrealizedbythemultiplexer-basedcircuit.)11111111四、(A)MinimizethelogicfunctionexpressionF=A·B+AC’+B’·C+BC’+B’D+BD’+ADE(H+G)（）F=A·B+AC’+B’·C+BC’+B’D+BD’=A·(B’C’+B’·C+BC’+B’D+BD’=A+CD或=A+CD’)=A+B’·C+BD’+CD(或=A+BC’+B’D+CD’)(B)TofindtheminimumsumofproductforFanduseNAND-NANDgatestorealizeit（6）FW,X,Y,Z)Π(1,3,4,6,9,11,12,14)3/9电子科技大学2010期末数字电子技术考试题A卷-参考答案1111111------3分-----2分1分F=XZ+XZ=(’+XZ)’’=((X’’)’(XZ)’五、Realizethelogicfunctionusingonechipof74LS139andtwoNANDgates.（8）F(,B,C)(2,6)GC,D,E)1111111111111111F(A,B,C)=C’∑(1,3)----3分G(C,D,E)=C’∑(0,2,3)----3分BA1XX000001010011111101110111011101114/9电子科技大学2010期末数字电子技术考试题A卷-参考答案-六、Designaself-correctingmodulo-6counterwithDflip-flops.Writeouttheexcitationequationsandoutputequation.QQQdenotethepresentstates,QQQdenotethenextstates,***210210Zdenotetheoutput.Thestatetransition/outputtableisas（10’）Z000001**21000100110111011001100110111011001000’2221111’’得分七、Constructaminimalstate/outputtableforamooresequentialmachine,thatwilldetecttheinputsequences:x=101.Ifx=101isdetected,thenZ=1.TheinputsequencesDONOToverlaponeanother.Thestatesaredenotedwith（10）Forexample:5/9电子科技大学2010期末数字电子技术考试题A卷-参考答案X：：101100011001000000state/outputtableXSZ10得分八、Pleasewriteoutthestate/outputtableandthetransition/outputtableandthe6/9电子科技大学2010期末数字电子技术考试题A卷-参考答案excitation/outputtableofthisstatemachine.（statesQ2Q1=00~11,usethestatenameA~D）（10）XXXSZZZ1100110111011101（4分）评分标准：转移/输出表正确，得4分；每错一处扣0.5分，扣完4分为止；（3分）（3分）由转移/输出表得到状态/输出表正确，得3分；每错一处扣0.5分，扣完3分为止；激励/输出表正确，得3分；每错一处扣0.5分，扣完3分为止。ClockedSynchronousStateMachine（15）74x163isasynchronous4-bitbinarycounterwithsynchronousCLEARinputand'''LOADinput.LD_L=(QQ),CLR_L=(QQ)inthefollowingcircuit.BCDB1.Finishthelogiccircuit.2.Drawthestatediagramwithallstatesof“Q3Q2Q1Q0”.(“Q3Q2Q1Q0”istheoutputof74x163)3.WritethesequenceofY.Yistheoutputof74x151.(Assumedstateof74x163startin7/9电子科技大学2010期末数字电子技术考试题A卷-参考答案Q3Q2Q1Q0=0000.)AB0