Computer operating system knowledge notes first part

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OS (Operating System)

Operating System Introduction

• ① operating system design target operating system and the role of
  • Configure the operating system on the computer system, its main objectives are: convenience , effectiveness , scalability and openness .
  • The role of OS are: as between the user and the computer hardware system interfaces , as the computer system resource manager , the realization of computer resources abstraction .
• The basic features of the operating system ②
  • Parallel and Concurrent : Parallelism refers to two or more events occur at the same time, concurrency refers to two or more events occur within the same time interval.
  • Share : Resource Sharing in OS environment called resource reuse refers to the system resources available memory in multiple processes concurrently executing common use. Method: exclusive sharing , simultaneous access mode .
  • Virtual : time division multiplexing technology use some free time to a customer service equipment, and turn to service for other users, to make the fullest use of equipment, space division multiplexing using the memory sub-regional free space to store and run other multi-channel program, improve memory utilization.
  • Asynchronous : In a single processor, assuming that the process submitted a request to use the printer, but the printer is being used, it needs to wait, that is to say it can not please with the process need to 'wait'.
• The main function of the operating system ③
  • Processor management: process control, process synchronization, interprocess communication, scheduling.
  • Memory management: memory allocation, memory protection, address mapping, memory expansion.
  • Device Management: buffer management, distribution equipment, processing equipment.
  • File management: read-write file storage management and protection management, directory management, file.
  • OS and user interface: The user (command) interfaces, program interface.
  • New features: system security, network functions and services to support multimedia.