Q1. 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.

Q2. Explain the concept of a process.

Q3. What is process scheduling? Explain various type of process schedulings.

Q4.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.