AL-501 Operating Systems - Nov 2023 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aWhat are the functionalities of Operating Systems? Explain in detail.
   How to answer

   • Define operating system and its role as resource manager and extended machine
   • List functionalities: process, memory, file, device, protection/security, user interface
   • Explain each functionality in detail with examples
2. 7 Marks
   bWhat is meant by a System call? How it can be used? How does an application program use these calls during execution?
   How to answer

   • Define system call and its need for kernel services
   • Explain how it is used - trap, parameter passing, kernel mode switch
   • Explain application program usage during execution with example and steps
3. 7 Marks
   aWrite about Disk Space Allocation Methods.
   How to answer

   • Define file allocation and need for disk space management
   • Explain contiguous allocation with merits/demerits
   • Explain linked and indexed allocation with diagram
4. 7 Marks
   bExplain about the services of operating system.
   How to answer

   • Define OS services and their purpose
   • Explain user services: UI, program execution, I/O, file, communication
   • Explain system services: resource allocation, accounting, protection
5. 7 Marks
   aWhat is a Monitor? Explain how dinning philosopher's problem is solved using monitors with example pseudo code.
   How to answer

   • Define monitor: high-level synchronization construct with condition variables
   • Explain procedures, mutual exclusion, wait/signal operations
   • Give pseudo-code solution to dining philosophers using monitor
6. 7 Marks
   b

   Following is the snapshot of a CPU

   Process CPU	Burst Arrival	Time
   P1	10	0
   P2	29	1
   P3	03	2
   P4	07	3

   Draw the Gantt chart and calculate the turnaround time and waiting time of the jobs for FCFS (First Come First Served), SJF (Shortest Job First), SRTF (Shortest Remaining Time First) and RR (Round Robin with time quantum 10) scheduling algorithms.

   How to answer

   • Tabulate burst and arrival times for P1-P4
   • Draw Gantt charts for FCFS, SJF, SRTF and RR (quantum 10)
   • Calculate turnaround time and waiting time for each algorithm and compare
7. 7 Marks
   aConsider the following page reference strings: 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 algorithm, assuming three, four frames? Remember that all frames are initially empty, so your first unique pages will cost one fault each.

   1. i)LRU replacement
   2. ii)Optimal replacement
   How to answer

   • State reference string 1 2 3 4 2 1 5 6 2 1 2 3 7 6 3 2 1 2 3 6 and frame counts 3 and 4
   • Simulate LRU replacement step-by-step and count faults for 3 and 4 frames
   • Simulate Optimal replacement step-by-step and count faults for 3 and 4 frames
8. 7 Marks
   bWhat is virtual memory? Discuss the benefits of virtual memory techniques.
   How to answer

   • Define virtual memory and separation of logical and physical memory
   • Explain demand paging / segmentation basis
   • Discuss benefits: larger address space, multiprogramming, protection, sharing
9. 7 Marks
   aExplain about deadlock conditions and Banker's algorithm in detail.
   How to answer

   • List four Coffman deadlock conditions: mutual exclusion, hold and wait, no preemption, circular wait
   • Explain each condition with example
   • Explain Banker's algorithm: safe state, need matrix, safety and resource-request steps
10. 7 Marks
    bWrite the principles of protection? And explain the access matrix in detail.
    How to answer

    • State principles of protection: least privilege, complete mediation, etc.
    • Define access matrix with domains, objects, rights
    • Explain implementation via ACL, capability lists with example
11. 7 Marks
    aWhat do you mean by Deadlock? Explain various methods of handling deadlock.
    How to answer

    • Define deadlock with example of resource wait cycle
    • Explain prevention, avoidance, detection and recovery
    • Compare methods and their use in OS
12. 7 Marks
    bExplain Paging Memory Management in detail.
    How to answer

    • Define paging: fixed-size pages, frames, page table
    • Explain address translation: page number and offset, TLB
    • Explain advantages like no external fragmentation and sharing/protection
13. 7 Marks
    aGiven memory partition of 100K, 500K, 200K, 300K, and 600K in order, How would each of the First-fit, Best-fit and Worst-fit algorithms place. The processes of 212K, 417K, 112K and 426K in order? Which algorithm makes the most efficient use of memory? Show the diagram of memory status in each case.
    How to answer

    • List partitions 100K, 500K, 200K, 300K, 600K and requests 212K, 417K, 112K, 426K
    • Show placement for First-fit, Best-fit, Worst-fit with memory status diagrams
    • Identify most efficient algorithm based on leftover and unallocated requests
14. 7 Marks
    bExplain Protection Mechanism illustrating use of Protection Domain and Access Control List.
    How to answer

    • Define protection domain and access rights
    • Explain Access Control List structure with example
    • Illustrate protection mechanism use with diagram
15. 14 Marks
    Write a short note on any two:

    1. i)Fixed Partitioning
    2. ii)Explain mutual exclusion problem
    3. iii)File System Creation
    4. iv)Embedded and Mobile Operating Systems
    How to answer

    • Select any two topics from the four options
    • Define and explain each with key points and examples
    • Give diagram or use-case where applicable