Operating Systems Multiprogramming Program A Run Walt Run Walt Program B Walt Run Walt Run Walt Program c wa缪 Walt Walt RunRun Run Run Rut Combined Walt Walt A B B TIme Multiprogramming with three programs Gao Haichang, Software School, Xidian University 14
Operating Systems Gao Haichang , Software School, Xidian University 14 Multiprogramming Multiprogramming with three programs
Operating Systems Spooling假脱机 Overlap l/o of one job with computation of anotherjob. while executing one job, the OS (重叠) E Reads next job from card reader into a storage area on the disk gob queue H Outputs printout of previous job from disk to printer Job pool- data structure that allows the os to select which job to run next in order to increase cpu utilization (作业池) Gao Haichang, Software School, Xidian University 15
Operating Systems Gao Haichang , Software School, Xidian University 15 Spooling 假脱机 Overlap I/O of one job with computation of another job. While executing one job, the OS: （重叠） Reads next job from card reader into a storage area on the disk (job queue). Outputs printout of previous job from disk to printer. Job pool – data structure that allows the OS to select which job to run next in order to increase CPU utilization. （作业池）
Operating Systems Time-Sharing Systems-Interactive Computing c The CPu is multiplexed among several jobs that are kept in memory and on disk (the cpu is allocated to a job only if the job is in memory).(复用) 矿 A job is swapped in and out of memory to the disk.(换入,换 出) e On-line communication between the user and the system is provided; when the operating system finishes the execution of one command it seeks the next control statement" not from a card reader, but rather from the user' s keyboard.(交互驱动) c On-line system must be available for users to access data and code(及时的处理数据和代码) Gao Haichang, Software School, Xidian University 16
Operating Systems Gao Haichang , Software School, Xidian University 16 Time-Sharing Systems–Interactive Computing The CPU is multiplexed among several jobs that are kept in memory and on disk (the CPU is allocated to a job only if the job is in memory). （复用） A job is swapped in and out of memory to the disk.（换入，换 出） On-line communication between the user and the system is provided; when the operating system finishes the execution of one command, it seeks the next “control statement” not from a card reader, but rather from the user’s keyboard. （交互驱动） On-line system must be available for users to access data and code.(及时的处理数据和代码)
Operating Systems GA OS Features Needed for Multiprogramming 1O routine supplied by the system.(ⅣO例程) g Memory management- the system must allocate the memory to several jobs.(内存管理) g CPU scheduling-the system must choose among severaljobs ready to run(CPU调度) G Allocation of devices.(设备管理) Gao Haichang, Software School, Xidian University 17
Operating Systems Gao Haichang , Software School, Xidian University 17 OS Features Needed for Multiprogramming I/O routine supplied by the system. （I/O例程） Memory management – the system must allocate the memory to several jobs.（内存管理） CPU scheduling – the system must choose among several jobs ready to run.（CPU调度） Allocation of devices.（设备管理）
Operating Systems Personal-Computer Systems (4) g Personal computers computer system dedicated to a single user Glo devices keyboards, mice, display screens, small printers gUser convenience and responsiveness Can adopt technology developed for larger operating system often individuals have sole use of computer and do not need advanced CPU utilization of protection features. Gao Haichang, Software School, Xidian University 18
Operating Systems Gao Haichang , Software School, Xidian University 18 Personal-Computer Systems（4） Personal computers – computer system dedicated to a single user. I/O devices – keyboards, mice, display screens, small printers. User convenience and responsiveness. Can adopt technology developed for larger operating system’ often individuals have sole use of computer and do not need advanced CPU utilization of protection features