软硬件系统编程PPT (20).pdf

什么是操作系统什么是操作系统？What is the operating system？Microcomputer System Computer SystemComputer System hardwarehardware softwaresoftware systemsystem softwaresoftware applicationapplication softwaresoftware OSOS systemsystem applicationsapplications Operating system What is the operating systemWhat is the operating system？3 What are its main functions?What are its main functions?What roles does it play in computers?What roles does it play in computers?Operating System(OS)Operating System is a set of programs which controls and manages software and hardware resources of the computer.Interface for user-computer communication.Functions：Manage system resources Provide a user-friendly interface 4 Processor,storage,input and output devices,and various information 5 OS hierarchy Hardware system File management Windows operating system interface user Data input and output;Data storage File access Powerful virtual machine Program data B005 0408 8804 5+8 memorymemory Must consider:How to input and output data?How to store and manage data Without OS,programs can only be written by Machine Instructions.I/O devices management,storage management It is the first layer of software on the hardware,and is a must for all types of computers.All other software run on the operating system.6 OS is.Hardware system OS Application software 1.Serving as an interface between users and computer hardware.Hide hardware so that users dont have to consider the differences among different hardware;Provide an interface for user-computer communication.7 Functions of OS through keyboard applications System System callcall OSOS useruser ordersorders 8 Functions of OS 2.Expansion of the functions of hardware system 3.Manage system resources OS can be seen as an orchestral conductor.One function is to manage and distribute hardware and software resources of computer system to make full use of them.One is to offer convenience for computer users.Through complicated processing internally,OS provides users with a friendly and convenient operating interface,so that they can use computers even without knowing the details of hardware and system software of computers.9 device management 存储器管理 storage management 处理器管理 processor management 用户接口 User interface 文件管理 文件管理 file management OS OS has five fundamental functions Classification of OS It has various types,but its main objective is to manage resources in different ways and efficiency for different applications under different circumstances so to meet the demands of different users.Batch processing system Time-sharing operating system Real-time operating system Embedded operating system Distributed operating system 10 A way that enables several terminals to share the same host CPU.CPU is divided into serval time pieces,and is distributed to all programs queuing for execution one by one,so that a CPU can execute multiple programs at a time.CPUCPU程序1程序2程序3程序nCPU时间片程序排队队列CPUCPUCPUCPU程序1程序2程序3程序nCPU时间片程序排队队列CPU time pieces Programs in line programs 1 programs 2 programs 3 programs n Time-sharing operating system