operatingsystemoverview(存儲版)
【正文】 ating system ? Machines run from a console with display lights(顯示燈 ), toggle switches（ 觸發(fā)器） , input device, and printer ? Computer systems were used in a serial fashion, meaning access to the puter was available in series. ? Programmers were directly interacting with the puter system. 12 Evolution of Operating Systems ? Schedule time(調(diào)度 ) ? imagine if some body has schedual to use it for 3 hours and some how finished in 30 minute. Therefore, the remaining 2 hours 30 minute are wasted as nothing is schedual for that period. ? Setup included loading the piler, source program, saving piled program（目標(biāo)程序） , and loading and linking 13 Evolution of Operating Systems ? Simple Batch Systems（ 簡單批處理） （ IBSYS） ? Monitors（ 監(jiān)控程序） ? Software that controls the sequence of events ? User no longer has direct access to the machine ? Batch jobs together sequentially, and used by the monitor ? Program branches back to monitor when finished 14 Two points to Simple Batch Systems ?Monitor point ? The monitor is the one controlling every thing. ? Much of the monitor must always be in main memory and available for execution, it is called resident monitor. ? When read in job, the control is passed to this job。 when it is pleted, it returns control to the monitor. 15 Two points to Simple Batch Systems ? Processor point ? The processor is executing instructions from the portion of main memory containing the monitor. ? When a job has been read in, the processor will encounter a branch instruction in the monitor that instructs the processor to continue execution at the start of the user program. ? When plete the job, the processor fetch its next instruction from the monitor program. 16 Hardware Features(硬件功能 ) The batch OS relies on the ability of processor to fetch instructions from various portions of main memory. Again, there are other hardware features: ? Memory protec
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