数字电子技术 英文

©2009PearsonEducation,UpperSaddleRiver,NJ07458.AllRightsReservedFloyd,DigitalFundamentals,10thedDigitalFundamentalsTenthEditionFloydChapter3©2008PearsonEducation©2009PearsonEducation,UpperSaddleRiver,NJ07458.AllRightsReservedFloyd,DigitalFundamentals,10thedTheinverterperformstheBooleanNOToperation.WhentheinputisLOW,theoutputisHIGH;whentheinputisHIGH,theoutputisLOW.SummaryTheInverterAXInputAXOutputLOW(0)HIGH(1)HIGH(1)LOW(0)TheNOToperation(complement)isshownwithanoverbar.Thus,theBooleanexpressionforaninverterisX=A.©2009PearsonEducation,UpperSaddleRiver,NJ07458.AllRightsReservedFloyd,DigitalFundamentals,10thedSummaryTheInverterExamplewaveforms:AXAXAgroupofinverterscanbeusedtoformthe1’scomplementofabinarynumber:Binarynumber1’scomplement1000110101110010©2009PearsonEducation,UpperSaddleRiver,NJ07458.AllRightsReservedFloyd,DigitalFundamentals,10thedTheANDgateproducesaHIGHoutputwhenallinputsareHIGH;otherwise,theoutputisLOW.Fora2-inputgate,thetruthtableisSummaryTheANDGateTheANDoperationisusuallyshownwithadotbetweenthevariablesbutitmaybeimplied(nodot).Thus,theANDoperationiswrittenasX=A.BorX=AB.InputsABXOutput000110110001ABX&ABX©2009PearsonEducation,UpperSaddleRiver,NJ07458.AllRightsReservedFloyd,DigitalFundamentals,10thedSummaryExamplewaveforms:AXTheANDoperationisusedincomputerprogrammingasaselectivemask.Ifyouwanttoretaincertainbitsofabinarynumberbutresettheotherbitsto0,youcouldsetamaskwith1’sinthepositionoftheretainedbits.TheANDGateABXB00000011Ifthebinarynumber10100011isANDedwiththemask00001111,whatistheresult?&ABX©2009PearsonEducation,UpperSaddleRiver,NJ07458.AllRightsReservedFloyd,DigitalFundamentals,10thedSummaryTheANDGateAMultisimcircuitisshown.XWG1isawordgeneratorsetinthecountdownmode.XLA1isalogicanalyzerwiththeoutputoftheANDgateconnectedtofirst(upper)lineoftheanalyzer.Whatsignaldoyouexpecttoonthisline?Theoutput(line1)willbeHIGHonlywhenalloftheinputsareHIGH.©2009PearsonEducation,UpperSaddleRiver,NJ07458.AllRightsReservedFloyd,DigitalFundamentals,10thedTheORgateproducesaHIGHoutputifanyinputisHIGH;ifallinputsareLOW,theoutputisLOW.Fora2-inputgate,thetruthtableisSummaryTheORGateTheORoperationisshownwithaplussign(+)betweenthevariables.Thus,theORoperationiswrittenasX=A+B.InputsABXOutput000110110111ABXABX≥1©2009PearsonEducation,UpperSaddleRiver,NJ07458.AllRightsReservedFloyd,DigitalFundamentals,10thedSummaryExamplewaveforms:AXTheORoperationcanbeusedincomputerprogrammingtosetcertainbitsofabinarynumberto1.TheORGateBABXABX≥1ASCIIlettershavea1inthebit5positionforlowercaselettersanda0inthispositionforcapitals.(Bitpositionsarenumberedfromrighttoleftstartingwith0.)WhatwillbetheresultifyouORanASCIIletterwiththe8-bitmask00100000?Theresultingletterwillbelowercase.©2009PearsonEducation,UpperSaddleRiver,NJ07458.AllRightsReservedFloyd,DigitalFundamentals,10thedSummaryTheORGateAMultisimcircuitisshown.XWG1isawordgeneratorsettocountdown.XLA1isalogicanalyzerwiththeoutputTheoutput(line1)willbeHIGHifanyinputisHIGH;otherwiseitwillbeLOW.connectedtofirst(top)lineoftheanalyzer.Thethree2-inputORgatesactasasingle4-inputgate.Whatsignaldoyouexpectontheoutputline?©2009PearsonEducation,UpperSaddleRiver,NJ07458.AllRightsReservedFloyd,DigitalFundamentals,10thedTheNANDgateproducesaLOWoutputwhenallinputsareHIGH;otherwise,theoutputisHIGH.Fora2-inputgate,thetruthtableisSummaryTheNANDGateInputsABXOutput000110111110ABXABX&TheNANDoperationisshownwithadotbetweenthevariablesandanoverbarcoveringthem.Thus,theNANDoperationiswrittenasX=A.B(Alternatively,X=AB.)©2009PearsonEducation,UpperSaddleRiver,NJ07458.AllRightsReservedFloyd,DigitalFundamentals,10thedSummaryExamplewaveforms:AXTheNANDgateisparticularlyusefulbecauseitisa“universal”gate–allotherbasicgatescanbeconstructedfromNANDgates.TheNANDGateBHowwouldyouconnecta2-inputNANDgatetoformabasicinverter?ABXABX&©2009PearsonEducation,UpperSaddleRiver,NJ07458.AllRightsReservedFloyd,DigitalFundamentals,10thedSummaryTheNANDGateAMultisimcircuitisshown.XWG1isawordgeneratorsetinthecountupmode.Afour-channeloscilloscopemonitorstheinputsandoutput.Whatoutputsignaldoyouexpecttosee?Theoutput(channelD)willbeLOWonlywhenalloftheinputsareHIGH.Inputs©2009PearsonEducation,UpperSaddleRiver,NJ07458.AllRightsReservedFloyd,DigitalFundamentals,10thedTheNORgateproducesaLOWoutputifanyinputisHIGH;ifallinputsareHIGH,theoutputisLOW.Fora2-inputgate,thetruthtableisSummaryTheNORGateInputsABXOutput000110111000ABXABX≥1TheNORoperationisshownwithaplussign(+)betweenthevariablesandanoverbarcoveringthem.Thus,theNORoperationiswrittenasX=A+B.©2009PearsonEducation,UpperSaddleRiver,NJ07458.AllRightsReservedFloyd,DigitalFundamentals,10thedSummaryExamplewaveforms:AXTheNORoperationwillproduceaLOWifanyinputisHIGH.TheNORGateBWhenistheLEDisONforthecircuitshown?TheLEDwillbeonwhenanyofthefourinputsareHIGH.ACBDX330W+5.0VABXABX≥1©2009PearsonEducation,UpperSaddleRiver,NJ07458.AllRightsReservedFloyd,DigitalFundamentals,10thedTheXORgateproducesaHIGHoutputonlywhenbothinputsareatoppositelogiclevels.ThetruthtableisSummaryTheXORGateInputsABXOutput000110110110ABXABX=1TheXORop