Questions
Syllabus
Qns. By Syllabus

Semester

Subject

Year

Tribhuwan University

Institute of Science and Technology

Model

Bachelor Level / Second Year / Third Semester / Science

Bachelors in Information Technology (BIT204)

(Operating Systems)

Full Marks: 60

Pass Marks: 24

Time: 3 Hours

Candidates are required to give their answers in their own words as for as practicable.

The figures in the margin indicate full marks.

Section A

Long Answers Questions

Attempt any TWO questions.
[2*10=20]
1.
Define critical section problem. Explain race condition with suitable example.[10]
2.
When does interrupt concur? Suppose that a disk drive has the cylinder numbered from 0 to 199. The head is currently at cylinder number 53. The queue for services of cylinders is as 99, 183, 37, 122, 14, 124, 65 and 67. What is the total head movement in each of following disk algorithm to satisfy the requests? (a) FCFS (b) SSTF (c) SCAN[10]
3.
What is page fault? Consider the following page reference string, 7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3, 2, 1, 2, 0, 1, 7, 0, 1. How many page faults would occur for each of the following page replacement algorithms assuming 3 frames? a. FIFO b. Second Chance c. LRU[10]
Section B

Short Answers Questions

Attempt any Eight questions.
[8*5=40]
4.
Explain about the transition between different states of a process. [5]
5.
Why do deadlock occurs? How can you detect and recover from deadlock. [5]
6.
Consider the following set of processes, with the length of CPU burst time given in milliseconds. Processes CPU Burst Priority A 8 3 B 13 1(Lowest) C 19 2 D 3 4(Highest) The processed are assumed to have arrived in the order A, B, C and D all at time 0. What is the turnaround time and waiting time for the scheduling algorithms, RR(quantum = 5) and Priority Algorithm

$\begin{array}{|c|c|c|}\hline \text{Processes} & \text{CPU Burst} & \text{Priority} \\ \hline A & 8 & 3 \\ B & 13 & 1\,(\text{Lowest}) \\ C & 19 & 2 \\ D & 3 & 4\,(\text{Highest}) \\ \hline \end{array}$
[5]
7.
Define swapping. How does the OS manage the virtual memory? [5]
8.
Define system call. Explain operating system as a extended machine. [5]
9.
How does process differ with thread? Discuss at least one multithreading model with its advantages and disadvantages. [5]
10.
How does DMA help in I/O management? Explain. [5]
11.
What does time sharing means in multiprogramming? Explain any three types of operating system structure. [5]
12.
Why do we need multiple queues in process scheduling? What is the significance of TLB? [5]