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1、CHAPTER8OperatingSystemsandUtilityProgramsOperatingSystemsWhatisOS?OperatingSystemisasoftware,whichmakesacomputertoactuallywork.Itisthesoftwaretheenablesalltheprogramsweuse.TheOSorganizesandcontrolsthehardware.OSactsasaninterfacebetweentheapplicationprogramsandthem
2、achinehardware.Examples:Windows,Linux,UnixandMacOS,etc.,WhatOSdoes?Anoperatingsystemperformsbasictaskssuchas,controllingandallocatingmemory,prioritizingsystemrequests,controllinginputandoutputdevices,facilitatingnetworkingandmanagingfilesystems.StructureofOperating
3、System:ApplicationProgramsSystemProgramsSoftware(OperatingSystem)HARDWARE(Contd…)StructureofOperatingSystem(Contd…):ThestructureofOSconsistsof4layers:HardwareHardwareconsistsofCPU,Mainmemory,I/ODevices,etc,Software(OperatingSystem)Softwareincludesprocessmanagementr
4、outines,memorymanagementroutines,I/Ocontrolroutines,filemanagementroutines.(Contd…)StructureofOperatingSystem(Contd…):SystemprogramsThislayerconsistsofcompilers,Assemblers,linkeretc.ApplicationprogramsThisisdependentonusersneed.Ex.Railwayreservationsystem,Bankdatab
5、asemanagementetc.,EvolutionofOS:Theevolutionofoperatingsystemswentthroughsevenmajorphases.Sixofthemsignificantlychangedthewaysinwhichusersaccessedcomputersthroughtheopenshop,batchprocessing,multiprogramming,timesharing,personalcomputing,anddistributedsystems.Inthes
6、eventhphasethefoundationsofconcurrentprogrammingweredevelopedanddemonstratedinmodeloperatingsystems.(Contd…)EvolutionofOS(contd..):MajorPhasesTechnicalInnovationsOperatingSystemsOpenShopTheideaofOSIBM701openshop(1954)BatchProcessingTapebatching,First-in,first-outsc
7、heduling.BKSsystem(1961)Multi-programmingProcessormultiplexing,Indivisibleoperations,Demandpaging,Input/outputspooling,Priorityscheduling,RemotejobentryAtlassupervisor(1961),ExecIIsystem(1966)(Contd…)EvolutionofOS(contd..):TimesharingSimultaneoususerinteraction,On-
8、linefilesystemsMulticsfilesystem(1965),Unix(1974)ConcurrentProgrammingHierarchicalsystems,Extensiblekernels,Parallelprogrammingconcepts,Securepar
