Abstract Vew of System Components Read摘要从系统组件读.pptVIP

Introduction What is an Operating System? Mainframe Systems Desktop Systems Multiprocessor Systems Distributed Systems Clustered System Real -Time Systems Handheld Systems Computing Environments What is an Operating System? A program that acts as an intermediary between a user of a computer and the computer hardware. An operating system is a program that manages the computer hardware. The purpose of an operating system is to provide an environment in which a user can execute programs in a convenient and efficient manner. Operating system goals: Execute user programs and make solving user problems easier. Make the computer system convenient to use. Use the computer hardware in an efficient manner. It is an important part of almost every computer system. Computer System Components 1. Hardware – provides basic computing resources (CPU, memory, I/O devices). 2. Operating system – controls and coordinates the use of the hardware among the various application programs for the various users. 3. Applications programs – define the ways in which the system resources are used to solve the computing problems of the users (compilers, database systems, video games, business programs). 4. Users (people, machines, other computers). Abstract View of System Components Operating System Definitions Resource allocator – manages and allocates resources. Control program – controls the execution of user programs and operations of I/O devices . Kernel – the one program running at all times (all else being application programs). Mainframe Systems The first computers used to tackle many commercial and scientific applications. Batch Systems – runs only one application Reduce setup time by batching similar jobs (to speed up processing) Automatic job sequencing – automatically transfers control from one job to another. Resident monitor initial control in monitor control transfers to job when job completes control transfers back to monitor Memory Layout for a Simple Batch System Multipr