Tribhuvan University · BCA Semester IV
BCA 4th Semester Operating System Past Questions
Collection of Tribhuvan University BCA 4th semester Operating System past questions from 2020, 2021 and 2023 for revision and exam preparation.
Exam pattern: Group B generally contains six 5-mark questions to attempt, while Group C contains two 10-mark questions. A few supplied questions contain transcription errors; unclear values are marked rather than invented.
Operating System Past Questions 2020
BCA Semester IV · CACS25160 Marks · Pass 24 · 3 Hours
Group B
Attempt any SIX · 6 × 5 = 302. What is an Operating System? Why is it known as the resource manager and the extended machine? [2+3]
3. What is Kernel? What role does it play in an Operating System? Differentiate between monolithic and micro kernel. [1+1+3]
4. A disk has 200 cylinders (0–200). The head pointer is at 50 and previously at 35. Pending requests are 60, 190, 40, 125, 15 and 150. Movement takes 6 msec per cylinder. Find total seek time using a) FCFS b) SCAN. [2.5+2.5]
5. Define file and directory. Explain Access Control List (ACL) and Access Control Matrix (ACM). [2+3]
6. What is biometric password in authentication? Explain various system threats. [2+3]
7. How is a distributed operating system more applicable than a centralized operating system? Explain major goals of a distributed operating system. [2+3]
8. Write short notes on any TWO: Producer Consumer problem; Coalescing and Compaction; Ubuntu. [2.5+2.5]
Group C
Attempt any TWO · 2 × 10 = 209. What is CPU scheduling? Write the criteria for CPU scheduling. For P0–P4, draw Gantt charts and calculate average waiting time and turnaround time using FCFS, SJF, non-preemptive priority and Round Robin (quantum = 1). All processes arrive at time 0.
| Process | Burst | Priority |
|---|---|---|
| P0 | 10 | 3 |
| P1 | 1 | 1 |
| P2 | 2 | 5 |
| P3 | 1 | 4 |
| P4 | 5 | 2 |
10. Define page fault and thrashing. For reference string 1, 3, 5, 1, 7, 1, 5, 5, 1, 4, 3, 7, 6, 3, 4, 1, find page faults with 3 frames using FIFO, LRU and Optimal page replacement.
11. Define deadlock. List conditions that result in resource deadlock and explain different deadlock handling methods. [2+1+7]
Operating System Past Questions 2021
BCA Semester IV · CACS25160 Marks · Pass 24 · 3 Hours
Group B
Attempt any SIX · 6 × 5 = 302. What is an operating system? Is a multitasking operating system better than a batch operating system? Justify. [1+4]
3. What is the role of scheduler? Differentiate between short-term and long-term scheduler. [2+3]
4. What is a race condition? Two concurrent processes have statements S1 and S2, with S2 required only after S1 completes. Write a semaphore solution. [1+4]
5. Explain CPU scheduling criteria. For the following multi-level queue scheduling problem, draw a Gantt chart and calculate average waiting and turnaround time. Queue 1 has higher priority, uses RR with quantum 2 ms; Queue 2 uses FCFS.
| Process | Arrival | Burst | Queue |
|---|---|---|---|
| P1 | 0 | 4 | 1 |
| P2 | 0 | 3 | 1 |
| P3 | 0 | 8 | 2 |
| P4 | 10 | 5 | 1 |
6. What is thrashing? Explain three memory management requirements. [1+4]
7. Given partitions of 100 KB, 500 KB, 200 KB, 300 KB and 600 KB, place processes 212 KB, 417 KB, 112 KB and 426 KB using First Fit, Best Fit and Worst Fit. Which is most efficient? [4+1]
8. When is programmed I/O suitable compared with other I/O techniques? Explain types of system threat. [1+4]
Group C
Attempt any TWO · 2 × 10 = 209. Use Banker’s algorithm to find the Need matrix, safe sequence, and whether request from P1 for (0,4,2,0) can be granted immediately. Note: the matrix referenced in the supplied text was missing, so it is not invented here.
10. How does Second Chance page replacement differ from FIFO? Explain Belady’s anomaly with an example. [5+5]
11. What is clock synchronization? Explain physical clock synchronization using Cristian’s algorithm and logical clock synchronization using Lamport’s algorithm with examples. [2+8]
Operating System Past Questions 2023
BCA Semester IV · CACS251 · Batch 202060 Marks · Pass 24 · 3 Hours
Group B
Attempt any SIX · 6 × 5 = 302. Define Operating System. Explain objectives of an Operating System. [1+4]
3. How can the producer-consumer problem be solved using semaphore? [5]
4. What are preemptable and non-preemptable resources? Describe necessary conditions for deadlock. [2+3]
5. Given memory partitions of 200K, 600K, 300K, 100K and 500K, place processes of 315K, 527K, 242K and 548K using First Fit, Best Fit and Worst Fit. Which is most efficient? [5]
6. What is meant by system threat? Explain different types of program threat. [1+4]
7. Explain methods of communication in a distributed system. [5]
8. Write short notes on any TWO: Access Control Matrix; Process State; Kernel. [2.5+2.5]
Group C
Attempt any TWO · 2 × 10 = 209. Processes P1–P5 arrive at time 0. Draw Gantt charts and calculate average waiting time and turnaround time using FCFS, Shortest Remaining Time Next, Priority and Round Robin (quantum = 2). Note: the process table in the supplied transcription is corrupted; verify the original paper before solving.
10. What are Disk Access Time and Disk Response Time? A disk has cylinders 0–199, current head 43 and previous request 25. Pending requests: 55, 58, 39, 18, 90, 160, 150, 38, 184. Find total head movement for FCFS, SSTF, C-SCAN and LOOK. [2+8]
11. Differentiate internal and external fragmentation. Explain examples and procedures to remove the two types of fragmentation. [4+6]
BCA 4th Semester Operating System Exam Preparation
Focus on repeated topics such as CPU scheduling, memory management, page replacement, deadlocks, disk scheduling, process synchronization, system threats, distributed operating systems and file management. For numerical questions, practice Gantt charts, page-replacement tables, memory allocation and disk-head movement.
More resources: BCA 4th Semester Study Materials · BCA Study Materials · Tribhuvan University Resources.