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1、MODERNOPERATINGSYSTEMSSECONDEDITIONPROBLEMSOLUTIONSANDREWS.TANENBAUMwww.khdaw.comVrijeUniversiteitAmsterdam,TheNetherlands课后答案网PRENTICEHALLUPPERSADDLERIVER,NJ07458SOLUTIONSTOCHAPTER1PROBLEMS1.Anoperatingsystemmustprovidetheuserswithanextended(i.e.,virtual)machine,anditmustmanagetheI/Odevicesandoth
2、ersystemresources.2.MultiprogrammingistherapidswitchingoftheCPUbetweenmultipleprocessesinmemory.ItiscommonlyusedtokeeptheCPUbusywhileoneormoreprocessesaredoingI/O.3.Inputspoolingisthetechniqueofreadinginjobs,forexample,fromcards,ontothedisk,sothatwhenthecurrentlyexecutingprocessesarefinished,therew
3、illbeworkwaitingfortheCPU.Outputspoolingconsistsoffirstcopyingprintablefilestodiskbeforeprintingthem,ratherthanprintingdirectlyastheoutputisgenerated.Inputspoolingonapersonalcomputerisnotverylikely,butoutputspoolingis.4.TheprimereasonformultiprogrammingistogivetheCPUsomethingtodowhilewaitingforI/Oto
4、complete.IfthereisnoDMA,theCPUisfullyoccu-pieddoingI/O,sothereisnothingtobegained(atleastintermsofCPUutili-zation)bymultiprogramming.NomatterhowmuchI/Oaprogramdoes,theCPUwillbe100percentbusy.Thisofcourseassumesthemajordelayisthewaitwhiledataarecopied.ACPUcoulddootherworkiftheI/Owereslowforotherrea
5、sons(arrivingonaserialline,forinstance).www.khdaw.com5.Secondgenerationcomputersdidnothavethenecessaryhardwaretoprotecttheoperatingsystemfrommalicioususerprograms.6.Itisstillalive.Forexample,IntelmakesPentiumI,II,andIII,and4CPUswithavarietyofdifferentpropertiesincludingspeedandpowerconsumption.All
6、ofthesemachinesarearchitecturallycompatible.Theydifferonlyinpriceandperformance,whichistheessenceofthefamilyidea.7.A25´80charactermonochrometextscreenrequiresa2000-bytebuffer.The1024´768pixel24-bitcolorbitmaprequires2,359,296bytes.In1980thesetwooptionswouldhavecost$10and$11,520,respectively.Forcur
7、rent课后答案网prices,checkonhowmuchRAMcurrentlycosts,probablylessthan$1/MB.8.Choices(a),(c),and(d)shouldberestrictedtokernelmode.9.Personalcomputersystemsarealwaysinteractive,oftenwithonlyasingleuser.Mainframesystemsn
