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1、Chapter3DigitalElectronics3.1IntroductionAcircuitthatemploysanumericalsignalinitsoperationisclassifiedasadigitalcircuit.Computers,pocketcalculators,digitalinstruments,andnumericalcontrol(NC)equipmentarecommonapplicationsofdigitalcircuits.Practicallyunlimitedquantitiesofdigitalinformationcanbe
2、processedinshortperiodsoftimeelectronically.Withoperationalspeedofprimeimportanceinelectronicstoday,digitalcircuitsareusedmorefrequently.Inthischapter,digitalcircuitapplicationsarediscussed.Therearemanytypesofdigitalcircuitsthathaveapplicationsinelectronics,includinglogiccircuits,flip-flopcir
3、cuits,countingcircuits,andmanyothers.Thefirstsectionsofthisunitdiscussthenumbersystemsthatarebasictodigitalcircuitunderstanding・TheremainderofthechapterintroducessomeofthetypesofdigitalcircuitsandexplainsBooleanalgebraasitisappliedtologiccircuits.3.2DigitalNumberSystemsThemostcommonnumbersyst
4、emusedtodayisthedecimalsystemjnwhich10digitsareusedforcounting.Thenumberofdigitsinthesystemiscalleditsbase(orradix).Thedecimalsystem,therefore,hasabaseof10.Numberingsystemshaveaplacevalue,whichreferstotheplacementofadigitwithrespecttoothersinthecountingprocess.Thelargestdigitthatcanbeusedinas
5、pecificplaceorlocationisdetenninedbythebaseofthesystem.Inthedecimalsystemthefirstpositiontotheleftofthedecimalpointiscalledtheunitsplace・Anydigitfrom0to9canbeusedinthisplace.Whennumbervaluesgreaterthan9areused,theymustbeexpressedwithtwoormoreplaces.Thenextpositiontotheleftoftheunitsplaceinade
6、cimalsystemisthetensplace.Thenumber99isthelargestdigitalvaluethatcanbeexpressedbytwoplacesinthedecimalsystem.Eachplaceaddedtotheleftextendsthenumbersystembyapowerof10.Anynumbercanbeexpressedasasumofweightedplacevalues.Thedecimalnumber2583,forexample,isexpressedas(2x1000)+(5x100)+(8x10)+(3x1).
7、Thedecimalnumbersystemiscommonlyusedinourdailylives.Electronically,however,itisratherdifficulttouse.Eachdigitofabase10systemwouldrequireaspecificvalueassociatedwithit,soitwouldnotbepractical.3.2.1BinaryNumberSystemElectronicdigitalsystemsareo
