Lesson4

4‐1EarlyDevelopmentsinElectronicDataProcessing

4‐2Mark14‐3TheEniac4‐4TheEdvac4–5ComputerGenerations4–6FirstGenerationComputers4–7SecondGenerationComputers4–8ThirdGenerationComputers4–9FourthGenerationComputer

  HowardAikenbeganworkontheMarkIatHarvardUniversity

 MarkIdigitalcomputerwascompletedin1944

 MarkIofficialnamewasAutomaticSequenceControlledCalculator.

 MarkIfunctions:  Couldperformarithmeticoperations  Couldlocateinformationstoredintabularform.

  Processednumbersupto23digitslongsandcouldmultiplythreeeight‐digitnumbersin1second.

  Itwasnotanelectroniccomputerbutasratheranelectromechanicalone

  ENIAC–ElectronicNumericalIntegratorandCalculator

  ENIACwasdevelopedbyPresperEckertJr.aandJohnMauchlyfrom1943to1946.

  Ithas18,000vacuumtubesandrequiredthemanualsettingofswitches.

  Itcouldperform300multiplicationspersecond

  EDVACisthemodifiedversionofENIAC  EDVAC–ElectronicDiscretevariableautomaticComputer

  EDVACemploysbinaryarithmetic  JohnvonNeumanninventedtheEDVAC

1.  FirstGenerationComputers2.  SecondGenerationComputers3.  ThirdGenerationComputers4.  FourthGenerationComputers

  Theusevacuumtubesinplaceofrelaysasameansofstoringdatainmemoryandtheuseofstored‐programconcept.

  Itrequires3.5KWofelectricityperdaytokeepthevacuumtubesrunning

  Solid‐statecomponents(transistorsanddiodes)andmagneticcorestorageformedthebasisforthesecondgenerationofcomputers

  Integratedsolid‐statecircuitry,improvedsecondarystoragedevicesandnewinput/outputdeviceswerethemostimportantadvancesinthisgeneration.

  Themajorinnovationswereinthedevelopmentofmicroelectronicsandinthedevelopmentofdifferentareasincomputertechnologysuchas:multiprocessing,multiprogramming,miniaturization,timesharing,operatingspeedandvirtualstorage.