Operating System BSSE term 4th Past Paper 2017 UOS

University of Sargodha

B.S. 4th Term Examination 2017

Subject: Software Engineer
Paper: Operating System (COMP-3621)
Time Allowed: 2.30 Hours
Maximum Marks: 60

Objective Part

(Compulsory)

Q. No. 1. Write short answers of the following in 2-3 lines on your answer sheet. (2*12)

i. What are the main purposes of an operating system?
ii. What is the purpose of system Calls?
iii. What is PCB?
iv. What is multithreading?
v. What is critical section?
vi. What is meant by the term dispatch latency?
vii. Write four necessary conditions for a deadlock to exist.
viii. Name two differences between logical and physical addresses
ix. What is virtual memory?
x. What is the cause of thrashing?
xi. What is a garbage collection?
xii. What is a disk controller?

Subjective Part

(3 * 12 = 36)

Q2. Explain different models of multithreading in detail.
Q3. What is the difference between paged and segmented memory management? Explain the difference by giving a suitable example of each.
Q4. What is Deadlock? Explain in detail how deadlock can be prevented?
Q5. Define File? Explain Access Methods in files.
Q6. Consider the following set of processes:

Processes are assumed to arrive in the order P1, P2, P3, P4, P5, and P6 all at time 0.
Use FCFS, SJF, Round Robin (quantum 2), and Priority (low numbers have high priority). For each of the algorithms:

i. Draw a Gantt chart
ii. Obtain the average waiting time
iii. Obtain the average turnaround time