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1、Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,1.,*,Click to edit Master title style,Houor 2011,Operating System Concepts 7,th,Edition,Jan 12,2005,Chapter 1:Introduction,Chapter 1:Introduction,What Operating Systems Do,Computer-System Organization,Computer-System
2、Architecture,Operating-System Structure,Operating-System Operations,Process Management,Memory Management,Storage Management,Protection and Security,Distributed Systems,Special-Purpose Systems,Computing Environments,Objectives,To provide a grand tour of the major operating systems components,To provi
3、de coverage of basic computer system organization,What is an Operating System?,A program that acts as an intermediary between a user of a computer and the computer hardware.,Operating system goals:,Execute user programs and make solving user problems easier.,Make the computer system convenient to us
4、e.,Use the computer hardware in an efficient manner.,Computer System Structure,Computer system can be divided into four components,Hardware provides basic computing resources,CPU,memory,I/O devices,Operating system,Controls and coordinates use of hardware among various applications and users,Applica
5、tion programs define the ways in which the system resources are used to solve the computing problems of the users,Word processors,compilers,web browsers,database systems,video games,Users,People,machines,other computers,Four Components of a Computer System,Operating System Definition,System view,OS
6、is a,resource allocator,Manages all resources,Decides between conflicting requests for efficient and fair resource use,OS is a,control program,Controls execution of programs to prevent errors and improper use of the computer,User view,Ease of use,PC,Resource utilization mainframe,Operating System De
7、finition(Cont.),No universally accepted definition,“Everything a vendor ships when you order an operating system”is good approximation,But varies wildly,“The one program running at all times on the computer”is the os(usually called the,kernel).,Everything else is either a system program(ships with t
8、he operating system)or an application program,Computer System Organization,Computer-system operation,One or more CPUs,device controllers connect through common bus providing access to shared memory,Concurrent execution of CPUs and devices competing for memory cycles,Computer Startup,bootstrap progra
9、m,is loaded at power-up or reboot,Typically stored in ROM or EPROM,generally known as,firmware,Initializates all aspects of system,Loads operating system kernel and starts execution,Computer-System Operation,I/O devices and the CPU can execute concurrently.,Each device controller is in charge of a p
10、articular device type.,Each device controller has a local buffer.,CPU moves data from/to main memory to/from local buffers,I/O is from the device to local buffer of controller.,Device controller informs CPU that it has finished its operation by causing an,interrupt,.,Common Functions of Interrupts,I
11、nterrupt transfers control to the interrupt service routine generally,through the,interrupt vector,which contains the addresses of all the service routines.,Interrupt architecture must save the address of the interrupted instruction.,Incoming interrupts are,disabled,while another interrupt is being
12、processed to prevent a,lost interrupt,.,A,trap,is a software-generated interrupt caused either by an error or a user request.,An operating system is,interrupt,driven.,Interrupt Handling,The operating system preserves the state of the CPU by storing registers and the program counter.,Determines which
13、 type of interrupt has occurred:,polling,vectored,interrupt system,Separate segments of code determine what action should be taken for each type of interrupt,Interrupt Timeline,I/O Structure,After I/O starts,control returns to user program only upon I/O completion.,Wait instruction idles the CPU unt
14、il the next interrupt,Wait loop(contention for memory access).,At most one I/O request is outstanding at a time,no simultaneous I/O processing.,After I/O starts,control returns to user program without waiting for I/O completion.,System call,request to the operating system to allow user to wait for I
15、/O completion.,Device-status table,contains entry for each I/O device indicating its type,address,and state.,Operating system indexes into I/O device table to determine device status and to modify table entry to include interrupt.,Two I/O Methods,Synchronous,Asynchronous,Device-Status Table,Direct M
16、emory Access Structure,Used for high-speed I/O devices able to transmit information at close to memory speeds.,Device controller transfers blocks of data from buffer storage directly to main memory without CPU intervention.,Only one interrupt is generated per block,rather than the one interrupt per byte.,Storage Structure,Main memory only large storage media that the CPU can access directly.,Secondary storage extension of main memory that provides large nonvolatile storage capacity.,Magnetic dis
操作系統(tǒng)概念第七版_第01章
