ANURAG GROUP OF INSTITUTIONS

(Autonomous)

B.Tech III Year I Semester Regular Examinations Nov/Dec - 2023

OPERATING SYSTEMS

(Computer Science and Engineering)

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Time: 3 Hours Max. Marks: 70

Note: Answer all questions from Part A and Part B.

PART - A (10 x 2 = 20 Marks)

1. Define Operating System. What are the main purposes of an operating system?
2. What are the various process states?
3. What is a race condition? How can it be avoided?

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4. List the necessary conditions for deadlock.
5. What are the differences between logical and physical addresses?
6. What is demand paging?
7. What is a file system? List the different types of file systems.
8. Explain briefly about file access methods.

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9. Differentiate between preemptive and non-preemptive scheduling.
10. What are the different types of system calls?

PART - B (5 x 10 = 50 Marks)

11. a) Explain different types of Operating System Structures. (OR)

b) Define Process. Explain the different operations on processes.

12. a) Explain the Banker's Algorithm for deadlock avoidance with an example. (OR)

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b) Explain the Readers-Writers Problem and its solutions.

13. a) Consider the following page reference string: 1, 2, 3, 4, 2, 1, 5, 6, 2, 1, 2, 3, 7, 6, 3, 2, 1, 2, 3, 6. How many page faults would occur for the following replacement algorithms, assuming three frames? Remember that all frames are initially empty:

1. FIFO replacement
2. LRU replacement
3. Optimal replacement (OR)

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b) Explain the concept of segmentation. What are its advantages and disadvantages?

14. a) What are the different directory structures? Explain with neat diagrams. (OR)

b) Explain different File Allocation Methods with neat diagrams.

15. a) Consider the following set of processes, with the length of the CPU burst time given in milliseconds:

The processes are assumed to have arrived in the order P1, P2, P3, P4, P5 all at time 0.

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i. Draw Gantt charts illustrating the execution of these processes using FCFS, SJF, a non-preemptive priority (a smaller priority number implies a higher priority), and RR (quantum = 1) scheduling.

ii. What is the turnaround time of each process for each of the scheduling algorithms in part a?

iii. What is the waiting time of each process for each of the scheduling algorithms in part a?

iv. Which of the algorithms results in the minimum average waiting time (over all processes)? (OR)

b) Explain the concept of disk scheduling. Explain different disk scheduling algorithms.

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