操作系统习题

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1、WORD格式可编辑1.1Whatarethethreemainpurposesofanoperatingsystem?Answer:•Toprovideanenvironmentforacomputerusertoexecuteprogramsoncomputerhardwareinaconvenientandefficientmanner.•Toallocatetheseparateresourcesofthecomputerasneededtosolvetheproblemgiven.Theallocationprocessshoul

2、dbeasfairandefficientaspossible.•Asacontrolprogramitservestwomajorfunctions:(1)supervisionoftheexecutionofuserprogramstopreventerrorsandimproperuseofthecomputer,and(2)managementoftheoperationandcontrolofI/Odevices.1.2Whatarethemaindifferencesbetweenoperatingsystemsformain

3、framecomputersandpersonalcomputers?Answer:Generally,operatingsystemsforbatchsystemshavesimplerrequirementsthanforpersonalcomputers.Batchsystemsdonothavetobeconcernedwithinteractingwithauserasmuchasapersonalcomputer.Asaresult,anoperatingsystemforaPCmustbeconcernedwithrespo

4、nsetimeforaninteractiveuser.Batchsystemsdonothavesuchrequirements.Apurebatchsystemalsomayhavenottohandletimesharing,whereasanoperatingsystemmustswitchrapidlybetweendifferentjobs.1.3Listthefourstepsthatarenecessarytorunaprogramonacompletelydedicatedmachine.Answer:a.Reserve

5、machinetime.b.Manuallyloadprogramintomemory.c.Loadstartingaddressandbeginexecution.d.Monitorandcontrolexecutionofprogramfromconsole.1.4Wehavestressedtheneedforanoperatingsystemtomakeefficientuseofthecomputinghardware.Whenisitappropriatefortheoperatingsystemtoforsakethispr

6、incipleandto“waste”resources?Whyissuchasystemnotreallywasteful?Answer:Single-usersystemsshouldmaximizeuseofthesystemfortheuser.AGUImight“waste”CPUcycles,butitoptimizestheuser’sinteractionwiththesystem.1.5Whatisthemaindifficultythataprogrammermustovercomeinwritinganoperati

7、ngsystemforareal-timeenvironment?Answer:Themaindifficultyiskeepingtheoperatingsystemwithinthefixedtimeconstraintsofareal-timesystem.Ifthesystemdoesnotcompleteataskinacertaintimeframe,itmaycauseabreakdownoftheentiresystemitisrunning.Thereforewhenwritinganoperatingsystemfor

8、areal-timesystem,thewritermustbesurethathisschedulingschemesdon’tallowresponsetimetoexceedthetim