1) The service and functions provided by an operating system can be divided into two main categories. Briefly describes the two categories and discuss how they differ.

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2) Explain the concept of a process.

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3) What is process scheduling? Explain various type of process schedulings.

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4) We consider 4 processes, A, B, C, D. We assume that the execution of

process requires:

For A: 7 CPU time units, 3 (I / O) time units and 5 CPU time units.

For B: 6 CPU time units, 4 (I / O) time units, 4 CPU time units.

For C: 5 CPU time units.

For D: 1 CPU time unit, 4 (I / O) time units and 2 CPU time units.

We suppose that

A is presented first, at time 0,

B occurs at time 1,

C is present at time 9,

D is present at time 12.

Show how the 4 processes will use the processor in each of the following cases:

1) Each process has its own (I / O) device and the scheduler works according to First In First Out "FIFO" (without pre-emption).

2) Each process has its own (I / O) device and the scheduler uses the turnaround algorithm, with a quantum of 5. The switching time is equal to 0. In this case, residence time of processes A, B, C and D.

3) The three processes use the same (I / O) device whose queue

waiting is handled FIFO. The scheduler of the processor uses the turnaround algorithm, with a quantum of 5. The switching time is assumed to be 0.