University of Sargodha
BS 1″ Semester (5* Intake) Exam 2026
Subject: CS & IT.
Paper: Operating Systems (CMPC-6201)
Time Allowed: 2:30 Hours
Maximum Marks: 40
Note: Objective part is compulsory. Attempt any three questions from subjective part.
(Illustrate your answer with diagram where needed)
Objective Part (Compulsory)
Q.1. Write short answers of the following in 2-3 lines of each on your answer sheet. (2*8)
1. What is Symmetric Multiprocessing?
2. Which System call is used in Windows to create a child process?
3. What is Race Condition?
4. Explain the purpose of Short-Term Scheduler.
5. What is Pure Demand Paging?
6.
When Hierarchical Page Map Tables are not efficient for structuring page map table?
7.
What is the drawback of one-to-one threading model?
usta din Why Peterson solution is not useful for multiprocessor architecture.
Subjective Part
ОГ (3*8)
Q2. Compute average turn-around time and average waiting time using SRTF and Round Robin
Scheduling Algorithm (time slice -3 units).
Arrival Time:
CPU Time:
7
3
4
5.
1
2
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Q3. a) Write down Dinning Philosopher solution using Semaphores.
[5]
b) Consider a logical address space of 512 pages with 64-KB page size, mapped onto a physical
memory of 128 frames. How many bits are required in the logical address? How many bits
are required in the physical address?
(3]
Q4. a) Consider the following page reference string:
3, 2, 7, 8, 2, 5, 7, 4, 6, 3, 8, 0, 5, 4, 6, 2, 7, 0, 8.
Assuming demand paging with three frames, calculate total number of page faults using
Optimal replacement algorithm?
[5]
b) Explain Producer Consumer Problem with examples.
[3]
Q5. Write down necessary conditions for deadlock. Explain Wait for Graphs in detail.
[8]
Q6. a) What is Virtual Memory? Discuss its benefits in detail.
(5]
b) Draw the diagram of paging hardware using Inverted Page Map Tables.
13]
—-LK-2516/23-04-2026—(F-25)-
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