Why is pin diagram of 7402 NOR gate reversed as compared ...

We observe that in every logic gate, the input pins are (1,2), (4,5), (9,10), (12,13) and output pins are (3), (6), (8), (11) but in case of ... ElectricalEngineeringStackExchangeisaquestionandanswersiteforelectronicsandelectricalengineeringprofessionals,students,andenthusiasts.Itonlytakesaminutetosignup. Signuptojointhiscommunity Anybodycanaskaquestion Anybodycananswer Thebestanswersarevotedupandrisetothetop Home Public Questions Tags Users Unanswered Teams StackOverflowforTeams –Startcollaboratingandsharingorganizationalknowledge. CreateafreeTeam WhyTeams? Teams CreatefreeTeam Teams Q&Aforwork Connectandshareknowledgewithinasinglelocationthatisstructuredandeasytosearch. Learnmore Whyispindiagramof7402NORgatereversedascomparedtoothergates? AskQuestion Asked 5years,1monthago Modified 7monthsago Viewed 11ktimes 3 \$\begingroup\$ Thefollowingisapictureofpindesignof74seriesTTLICFamilylogicgatestakenfromthissite: Weobservethatineverylogicgate,theinputpinsare(1,2),(4,5),(9,10),(12,13)andoutputpinsare(3),(6),(8),(11)butincaseof7402NORgate,theinputandoutputpinsarereversedi.e.inputpinsare(2,3),(5,6),(8,9),(11,12)andoutputpinsare(1),(4),(10),(13).Whyisthisso?Whyisthepinsreversedincaseof7402NORgate?ThefollowingpictureclearlydepictswhatIamtryingtosay(takenfromthisdatasheet): Isitduetostructuralplanning,stabilityorsomeotherreason?TheIcouldn'tfindanyreasoningontheinternetandneedsomehelp.Also,whatwouldhappenifweconnectNORgateaswedoinothergates? logic-gatespins Share Cite Follow askedMay21,2017at5:54 ShadowShadow 54122goldbadges1010silverbadges2020bronzebadges \$\endgroup\$ 5 \$\begingroup\$ theseweregrandfatheredfromTTLsystemdesignrequirementsandnoreasontochangeforCMOS \$\endgroup\$ – TonyStewartEE75 May21,2017at7:08 \$\begingroup\$ Hithereandwelcometothesite.TheseICswerefirstmadeinthe1960s,whensiliconchipmanufacturingwasverymuchinitsinfancy,soIcanonlyguess.There'snoapplicationbenefitIcanthinkof.CanIaskwhyyouwantedtoknow-wasitjustcuriousityordoesitaffectsomethingyou'reworkingon? \$\endgroup\$ – TonyM May21,2017at7:12 \$\begingroup\$ @TonyMItisjustcuriosity.JustwentthroughdifferentlogicgatesandobservedwhyNORgatehasdifferentpindiagram.Therehastobesomereasonwhyitisdifferent. \$\endgroup\$ – Shadow May21,2017at13:05 1 \$\begingroup\$ Probablysomethingdull.Theywerelaidoutbydifferentengineers...Itwasanattemptatbringingbettermanufacturingyieldthroughadifferentlayoutidea...Theywishitwasthesamebuttheguyhaddoneallthelayoutbythen...I'dguessthatit'llbeafarlessexcitingreasonthanyoumightimagine:-) \$\endgroup\$ – TonyM May21,2017at13:13 \$\begingroup\$ Idon'tknowbutIhavewantedtohaveasterntalkwiththeguywhodiditeversinceItookdigitalinCollegein1976.NowIteachDigitalElectronicsatalocalUniversityandmystudentsfeelthesameway.Wejusthadalabthatuseda74LS02andeventhoughIwarnedthem,severalwireduptheirbreadboardswrongandwerenothappyaboutit. \$\endgroup\$ – markshancock Dec13,2021at2:58 Addacomment  |  1Answer 1 Sortedby: Resettodefault Highestscore(default) Datemodified(newestfirst) Datecreated(oldestfirst) 4 \$\begingroup\$ Weobservethatineverylogicgate,theinputpinsare(1,2), (4,5),(9,10),(12,13)andoutputpinsare(3),(6),(8),(11)but incaseof7402NORgate,theinputandoutputpinsarereversed Er,nowedon't.The74266doesn'tfollowthesupposed'standard'pinout.Alsothe7401QuadOpenCollectorNAND,7439QuadOpenCollectorNAND,7428QuadNORand7433QuadOpenCollectorNORgatesallhavethesamepinoutasthe7402. Isuspecttheoriginalreasonforthedifferentpinoutswastogetthemostefficientlayoutonthechip. Here'sanannotatedphotoofa7400die:- Andhere'sa74LS01:- WeobservethattheyarelaidoutinoppositedirectionsrelativetoVCCandGND,whichexplainsthedifferentpinout.Thefactthatseveralgatesfollowedthesamelayoutasthe7401suggeststhattherewasanadvantagetodoingitinthisdirection. Share Cite Follow answeredDec13,2021at10:00 BruceAbbottBruceAbbott 51.5k11goldbadge4444silverbadges8181bronzebadges \$\endgroup\$ Addacomment  |  YourAnswer ThanksforcontributingananswertoElectricalEngineeringStackExchange!Pleasebesuretoanswerthequestion.Providedetailsandshareyourresearch!Butavoid…Askingforhelp,clarification,orrespondingtootheranswers.Makingstatementsbasedonopinion;backthemupwithreferencesorpersonalexperience.UseMathJaxtoformatequations.MathJaxreference.Tolearnmore,seeourtipsonwritinggreatanswers. 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