西安交通大学操作系统原理第一章.ppt

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1、1Introduction操作系统引论Whatisanoperatingsystem?DevelopmentandTypesofOSThefeaturesofOSThefunctionsofOSComputerSystemOrganizationOneormoreCPUs,devicecontrollersconnectthroughcommonbusprovidingaccesstosharedmemoryConcurrentexecutionofCPUsanddevicescompetingform

2、emorycyclesComputer-SystemOperationI/OdevicesandtheCPUcanexecuteconcurrentlyEachdevicecontrollerisinchargeofaparticulardevicetypeEachdevicecontrollerhasalocalbufferCPUmovesdatafrom/tomainmemoryto/fromlocalbuffersI/Oisfromthedevicetolocalbufferofcontrolle

3、rDevicecontrollerinformsCPUthatithasfinisheditsoperationbycausinganinterruptCommonFunctionsofInterruptsInterrupttransferscontroltotheinterruptserviceroutinegenerally,throughtheinterruptvector,whichcontainstheaddressesofalltheserviceroutinesInterruptarchi

4、tecturemustsavetheaddressoftheinterruptedinstructionAtrapisasoftware-generatedinterruptcausedeitherbyanerrororauserrequestAnoperatingsystemisinterruptdrivenAbstractViewofSystemstructureComputersystemstructureHardware–providesbasiccomputingresources(CPU,m

5、emory,I/Odevices).提供基本的运算资源Operatingsystem–controlsandcoordinatestheuseofthehardwareamongthevariousapplicationprogramsforthevarioususers.在各种应用程序和用户之间控制与协调对硬件的使用Computersystemstructure(cont.)Applicationsprograms–definethewaysinwhichthesystemresourcesareus

6、edtosolvethecomputingproblemsoftheusers(compilers,databasesystems,videogames,businessprograms).应用程序-定义解决用户问题的资源使用方式（编译、数据库、视频游戏、事务程序等）Users(people,machines,othercomputers)用户（人、机、其他计算机）.Resourcesincomputersystem计算机系统资源硬件资源软件资源指构成计算机系统所必须的那些“硬”设备主机中央处理机CPU

7、内存外部设备程序和数据的集合系统软件（OS、Compiler、DBMS）应用软件（CAD、MIS、用户自己开发的系统等）工具软件（软、硬件检测诊断程序）I/O设备（键盘、显示器、打字机、鼠标）存储设备（硬盘、软盘、光盘、磁带）其它设备（MODEM、通信口）UsermodeandkernelmodeDual-modeoperationallowsOStoprotectitselfandothersystemcomponentsUsermodeandkernelmodeModebitprovidedbyha

8、rdwareProvidesabilitytodistinguishwhensystemisrunningusercodeorkernelcodeSomeinstructionsdesignatedasprivileged,onlyexecutableinkernelmodeSystemcallchangesmodetokernel,returnfromcallresetsittouserTransitionfromUsertoKernel