CACS251 Operating System

Operating System TU Board 2026 question paper

10 questionsSit this paper (timed)

Tribhuvan University

Bachelor of Computer Application

Semester 4 · TU Board 2026

Course Title: Operating System (CACS251)

Full Marks: 60Pass Marks: 24Time: 3 hours

Candidates are required to answer the question in their own words as far as possible.

Group B

Attempt any SIX question.(6 × 5 = 30)

  1. 2.

    What is a monolithic kernel? How is it different from microkernel? Explain. [1+4]

    5
  2. 3.

    What is multithreading? Explain different types of threads. [1+4]

    5
  3. 4.

    Explain the different process states in detail. [5]

    5
  4. 5.

    What are the necessary conditions for the deadlock? How deadlock is different from starvation? [4+1]

    5
  5. 6.

    What is segmentation? How can it be used for the memory management? [1+4]

    5
  6. 7.

    What are different page replacement algorithms? Explain. [5]

    5
  7. 8.

    List some security problems in operating system. Explain the role of clock synchronization in distributed system. [2+3]

    5

Group C

Attempt any TWO questions(2 × 10 = 20)

  1. 9.

    What is producer consumer problem? Explain the solutions of producer consumer problem using sleep and wakeup and compare it with the solution using semaphores. [1+4+5]

    10
  2. 10.

    Consider the following resource allocation state: AllocationMaxAvailableABCDABCDABCDP₀001200121520P₁10001750P₂13542356P₃06320652P₄00140656 Find the need matrix. Using Bankers algorithm, check whether the system is in safe state or not? If yes, find the execution order of the processes. [10]

    10
  3. 11.

    What are seek time and disk access time? Suppose that a disk drive has 5,000 cylinders, numbered 0 to 4,999. The drive is currently serving a request at cylinder 2,150, and the previous request was at cylinder 1,805. The queue of pending requests, in FIFO order, is: 2069, 1212, 2296, 2800, 544, 1618, 356, 1523, 4965, 3681. Starting from the current head position, what is the total distance (in cylinders) that the disk arm moves to satisfy all the pending requests for each of the following disk-scheduling algorithms? a) FCFS b) SSTF c) C-SCAN d) C-LOOK [2+8]

    10

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