1.What is the average time to read or write a 256-byte sector for a typeical disk rotating at 7200 PRM ? The advertised average seek time is 8 ms,the transfer rate is 1 MB/sec. Assume that the disk is idle so that there is no waiting time. 2.Assume that any individual program spends 40% of its time waiting for I/O operations to be completed. What percentage of time is the processor doing useful work (called processor utilization) if there are three programs loaded into memory ? How many programs should we keep in memory if we want processor unilization to be at least 90%? 请问版友这两题如何算 可以教导一下吗? --

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