Current Affairs
PGDCA Previous Year Questions (OS)
Read the important current affairs of 15 July 2026 for SSC, Banking, UPSC, Railway and all competitive exams.
18
November 20242. Consider the following set of processes, with the length of CPU burst time given in milliseconds :
Process CPU burst time
P1 10
P2 8
P3 4
P4 6
All the four processes (P1, P2, P3, P4) arrived at the same time in the order P1, P2, P3 and P4. Draw Gantt charts illustrating the execution of the processes using SJF,
FCFS and RR (Quantum = 2) scheduling. What is the turnaround time of each process for each of the scheduling algorithms ? Also find the average waiting
time for each of the processes.
3. Define virtual memory. Explain the principles of operation and the address mapping scheme of it. Also, write briefly
about the protection and sharing in virtual memory.
4. With reference to Android operating system explain the layered architecture and its components. Also draw the layered
architecture components. diagram indicating its
5. Describe the difference between security policy vs. security model in the context of operating system. Briefly explain the following security models :
(i) Access Matrix Model
(ii) Discretionary Access Control
6. With the help of an example, explain the linked/chained allocation scheme of non contiguous memory allocation.
7. Define an overlay with the help of an example. Explain the allocation scheme using overlays. How is this scheme different from swapping ?
8. Define deadlock. List and explain four necessary conditions that must hold simultaneously for a deadlock to occur.
9. When does a page fault occur in demand paging ? Describe the action taken by the operating system when it occurs.
10. What is Disk Scheduling ? With the help of an example for each, explain the following disk scheduling algorithms :
(i) FCFS
(ii) SSTF
(iii) Round Robin
(iv) Priority-based Scheduling
11. Define a semaphore. Using semaphores, write and explain the algorithm that solves the Reader’s and Writer’s problem.
12. Discuss the security features in LINUX with respect to the following :
(i) User Accounts
(ii) File Permissions
(iii) Encrypted Storage
(iv) Remote Access
13. There are three main alternative ways to structure a distributed application as shown below :
(i) Client/Server (and RPC)
(ii) Distributed objects
(iii) Distributed shared memory
Explain all the three models with the help of block diagrams respectively.
14. Discuss the following mechanisms/ techniques suitable for synchronization in multiprocessors :
(i) Test-and-set
(ii) Compare-and-swap
15.a. Describe the evolution of iOS. Also, discuss the features of iOS operating system.
b. Explain the file management system in iOS and also briefly mention the security aspects of file system.
16. Explain the process management and process scheduling in Windows-10.
17. With reference to wireless communication, explain the configuration’ communication :
(i) following ways Infrared connection ‘two-unit of device
(ii) Bluetooth connection
(iii) Near Field Communication (NFC)
Also mention the drawbacks, if any, with the ‘two-unit configuration’ model/technique.
18. Explain the memory management in Android Operating System.
19. Write and explain the Lamport’s Scheme of Ordering of Events in Distributed Systems.
20. Describe briefly Demand Paging in WINDOWS-10.
21. Briefly explain the two non-contiguous disk storage allocation schemes, with the help of an illustration for each.
22. Describe the process management in LINUX which includes process priorities, process hierarchy, process states and threads management.
23. With the help of a simple block diagram, explain the XNU kernel architecture which was initially used for Mac OS.
24. Define Segmentation Scheme. With the help of a diagram, explain the principles of its operation.
25. Define Thrashing and explain the reason of its occurrence, with the help of an example. Describe briefly the prevention of thrashing.
26. List the contents of a Process Control Block (PCB). Explain the significance of each of its components.
27. Using SSTF and C-SCAN disk scheduling algorithms, calculate the total head movement for the following block
sequence : 61, 141, 40, 160, 15, 63, 60, 125
Note : Initially the head is at cylinder numbered 0.
28. Define segmentation. Explain with the help of a diagram, the address mapping scheme used in segmentation.
29. With the help of a diagram, explain the fundamental architecture of LINUX operating system.
30. Write and explain “Banker’s algorithm” for Deadlock Avoidance proposed by Dijkstra
31. List and explain the design issues involved in distributed systems.
32. With the help of a diagram, explain “Distributed Shared Memory” application model.
33. Describe multiprocessor OS functions and requirements. With synchronization respect to in multiprocessors, explain test-and-set, compare-and-swapes and fetch-and-add techniques.
34. Write briefly about the following types of processors used in mobile devices :
(i) Qualcomm Snapdragon
(ii) Intel Atom Processor
35. Write short notes on any four of the following :
(a) Design issues in Mobile OS
(b) File system management in Windows 10
(c) Security features in LINUX
(d) Memory management in Android
(e) iOS directories and iCloud container of iOS
(f) Demand segmentation
(g) Deadlock avoidance
(h) Windows vs. Linux operating system
(i) Remote Procedure Call (RPC)
(j) Process and thread management in iOS
(k) IPC mechanisms in Android
(l) File management in LINUX operating system
(m) File permissions, data verification, encrypted storage and remote access in Linux operating system.
(n) Inter-process communication in Windows 10
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