(a) Section 1.5 discusses how the input and output steps of a collection of programs such as the one shown in Figure 1.4 could be overlapped to reduce the total time needed to execute them. Let each of the six OS routine execution intervals be 1 unit of time, with each disk operation requiring 3 units, printing requiring 3 units, and each program execution interval requiring 2 units of time. Compute the ratio of best overlapped time to nonoverlapped time for a long sequence of programs. Ignore start-up and ending transients.

(b) Section 1.5 indicated that program computation can be overlapped with either input or output operations or both. Ignoring the relatively short time needed for OS routines, what is the ratio of best overlapped time to nonoverlapped time for completing the execution of a collection of programs, where each program has about equal balance among input, compute, and output activities?

LO1