资源描述：
《电气工程与自动化专业英语 教学课件 作者 王伟 3.pptx》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。
1、3.1 IntroductionAcircuitthatemploysanumericalsignalinitsoperationisclassifiedasadigitalcircuit.Computers,pocketcalculators,digitalinstruments,andnumericalcontrol(NC)equipmentarecommonapplicationsofdigitalcircuits.Practicallyunlimitedquantitiesofdigitalinformationcanbeprocessedinshortperio
2、dsoftimeelectronically.Withoperationalspeedofprimeimportanceinelectronicstoday,digitalcircuitsareusedmorefrequently.13.2 DigitalNumberSystems3.2.1 BinaryNumberSystem3.2.2 Binary-codedDecimal(BCD)NumberSystem3.2.3 OctalNumberSystem3.2.4 HexadecimalNumberSystem3.2.1 BinaryNumberSystemElectr
3、onicdigitalsystemsareordinarilythebinarytype,whichhas2asitsbase.Onlythenumbers0or1areusedinthebinarysystem.Electronically,thevalueof0canbeassociatedwithalow-voltagevalueornovoltage.Thenumber1canthenbeassociatedwithavoltagevaluelargerthan0.Binarysystemsthatusethesevoltagevaluesaresaidtohav
4、epositivelogic.Negativelogic,bycomparison,hasavoltageassignedto0andnovoltagevalueassignedto1.Positivelogicisusedinthischapter.3.2.2 Binary-codedDecimal(BCD)NumberSystemWhenlargenumbersareindicatedbybinarynumbers,theyaredifficulttouse.Forthisreason,theBinary-CodedDecimal(BCD)methodofcounti
5、ngwasdevised.Inthissystemfourbinarydigitsareusedtorepresenteachdecimaldigit.Toillustratethisprocedure,thenumber105,isconvertedtoaBCDnumber.Inbinarynumbers,10510=1,000,1012.3.2.3 OctalNumberSystemTheoctal(base8)numbersystemisusedtoprocesslargenumbersbydigitalcircuits.Theoctalsystemofnumber
6、susesthesamebasicprinciplesasthedecimalandbinarysystems.Theoctalnumbersystemhasabaseof8.Thelargestnumberusedinabase8systemis7.Theplacevaluesstartingattheleftoftheoctalpointarethepowersofeight:80=1,81=8,82=64,83=512,84=4,096,andsoon.3.2.4 HexadecimalNumberSystemThehexadecimalnumbersystemis
7、usedindigitalsystemstoprocesslargenumbervalues.Thebaseofthissystemis16,whichmeansthatthelargestnumberusedinaplaceis15.Digitsusedbythissystemarethenumbers0-9andthelettersA-F.ThelettersA-Fareusedtodenotethedigits10-15,respectively.Theplacevaluestotheleftofthehexadecim
