Operating System — CACS251 (4th Sem)

fs) ¥ -~ @ ® e ay Tribhuvan University We Oe Faculty of Humanities & Social Sciences ys - @e@. y OFFICE OF THE DEAN a a ak 3 2023 Bachelor in Computer Applications Full Marks: 60 Course Title: Operating System Pass Marks: 24 Code No: CACS251 Time: 3 hours Semester: IV Batch: 2020 Candidates are required to answer the questions in their own words as far as possible. Group B Attempt any SIX questions. [6x5 = 30} 2.. Define Operating System? Explain objectives of Operating System. [1+4] 3. How can we solve producer-consumer problem semaphore? [5] _4- What do you mean by Preemptable and Non-Preemptable resources? Describe the necessary conditions for deadlock. [2+3] 5. Given memory partitions of 200k, 600k, 300k, 400k and 700k (in order), how would each of the First-fit, Best-fit and Worst-fit algorithms place processes of 315k, 527k, 202k and 548k (in order)? Which algorithm makes the most efficient use of memory? [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): P2525 a) Access Control Matrix b) Process States c) Kernel Group C Attempt any TWO questions. = [2x10 = 20] 9. The processes are assumed to have arrived in the order pl, p2, p3, p4, p5 all at time 0. Draw ’ Gantt chart illustrating their execution and calculate average waiting time and turnaround time for the process given below using: [10] a) First Come First Serve b) Shortest Remaining Time Next c) Priority d) Round Robin (quantum = 2) Burst Time (See) Pi SPs: See es ane sean oe |e ae ee SE | 3 | 10. What is Disk Access Time and Disk Response Time? Suppose that a disk has 200 cyli numbered (0-199). The drive is currently serving a request at cylinder 43 and previous a at cylinder 25. The queue of pending request, in FIFO order is: 55, 58, 39, 18, 90, 160, 150. 38. 184 Starting from the current head position, what is total distance (in evlind’rs) that the disk a es to satisfy all pending request for each of following disk Scheduling algorithms? a x oa a) FCFS b) SSTF c) C-SCAN d) LOOK [2+8] 11. Differentiate between internal and external fragmentation? Explain bri i procedure to remove the types of fragmentation. pared win oe Ves