操作系统-精髓与设计原理英文-Chapter02.ppt

Operating System Overview Chapter 2 Operating System A program that controls the execution of application programs A resource management software Designer viewpoint An interface between applications and hardware A virtual machine User viewpoint Operating System Objectives Convenience Makes the computer more convenient to use Efficiency Allows computer system resources to be used in an efficient manner Ability to evolve Permit effective development, testing, and introduction of new system functions without interfering with service Layers of Computer System Services Provided by Operating Systems Program development Editors and debuggers Program execution Access to I/O devices Controlled access to files System access Services Provided by Operating Systems Error detection and response Internal and external hardware errors Memory error Device failure Software errors Arithmetic overflow Access forbidden memory locations Operating system cannot grant request of application Services Provided by Operating Systems Accounting Collect usage statistics Monitor performance Used to anticipate future enhancements Used for billing purposes Operating Systems as Resource Managers Responsible for managing resources Functions same way as ordinary computer software It is program that is executed Operating system relinquishes control of the processor Ease of Evolution of an Operating System Hardware upgrades plus new types of hardware New services in response to user demand or in response to the needs of system managers Fixes any OS has faults Evolution of Operating Systems Serial Processing No operating system Machines run from a console with display lights, toggle switches, input device, and printer Schedule time Setup included loading the compiler, source program, saving compiled program, and loading and linking Evolution of Operating Systems Simple Batch Systems Monitors Software that controls the sequence of events Batch jobs together Program branches back to monitor when finished