Punjabi University 2008 B.C.A Computer Application OPERATING SYSTEMS - Question Paper

BCA:Operating System ques. Paper 2008

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CS1252 - OPERATING SYSTEMS

Time: 3 hours Maximum: 100 marks

ans ALL ques..

PART A – (10 x 2=20 marks)

1.Define Real Time Operating System.
2.Define SYSTEM CALLS.
3.What do you mean by a critical part problem?
4.Define the use of monitor.
5.Describe the 4 necessary conditions for deadlocks.
6.Why should paging be used by operating systems?
7.Define virtual memory.
8.What is the reason of thrashing?
9.What is the Kernel of an operating system?
10.Mention the importance of swap-space management.

PART B - (5 x 16 = 80 marks)

11. (a) (i)How does multi programming help in achieving improved utilization of a computer
system?[Marks 8]
(ii)With necessary diagram discuss the term "process" from the operating system point of view.[Marks 8]

Or
(b) (i)Briefly discuss the 4 major functions of an operating system.[Marks 8]
(ii)Give the main feature of the subsequent kinds of OS outlining their limitations and strengths : Interactive Time sharing OS, Real Time OS. [marks 8]

12. (a) Consider the subsequent set of processes, with the length of CPU-burst time provided in millisecond. [marks 16]
Process Burst time Priority
p1 10 3
p2 one 1
p3 two 3
p4 one 4
p5 five 2
The processes are presumed to have arrived in order p1,p2,p3,p4,p5 all at time 0. (i) Draw Gantt chats illustrating the execution of these processes using FCFS, SJF, a non-preemptive priority ( a smaller priority number implies a higher priority) and RR (quantum=1) scheduling (ii) What is the turn around time of every process for every of the scheduling algorithms in part (i)?

Or
(b) (i)What 2 advantages do threads have over multiple processes?
What major disadvantage do they have? Suggest 1 application that would benefit from the use of threads, and 1 that would not. [marks 6]
(ii) describe the requirement of the accurate solution.How semaphores are used to solve dining philosophers issue. [marks 10]

13. (a) An operating system contains 3 resource classes, namely R1, R2 and R3. The number of resource units in these classes is 7,7 and 10 respectively.The current resource allocation state is as shown beneath :[marks 16]
Process Allocated Resources Maximum Requirement

R1 R2 R3 R1 R2 R3

P1 two 2 three 3 six 8

P2 two 0 three four three 3

P3 one two four three four 4

(i) Is the current allocation state safe?[Marks 4]
(ii)Would the subsequent requests be granted in the current state?
(1) Process P1 requests(1, 1, 0) [Marks 4]
(2) Process P3 requests(0, 1, 0) [Marks 4]
(3) Process P2 requests(0, 1, 0) [Marks 4]

Or
(b) (i)Explain a few of the most common techniques for structuring the page table. [marks 8]
(ii)Explain the princples of segmentation with examples. [marks 8]

14. (a) Consider the subsequent page reference string : [marks 16]
1,2,7,8,3,4,2,1,4,2,5,6. How many page faukts would occur for the subsequent page replacement algorithms, assuming an allocation of three frames?

(i) LRU [marks 5]
(ii) FIFO [marks 5]
(iii) Optimal. [marks 6]

Or
(b) (i) discuss the concept of demand paging. [marks 8]
(ii) How does the system detect trashing? Once it detect trashing what the system do to eliminate this problem? [marks 8]

15. (a) (i) define the salient features of the file system of UNIX. [marks 8]
(ii)Explain UNIX buffer cache mechanism. [marks 8]

Or
(b) (i) discuss various disk scheduling Techniques. [marks 8]
(ii) discuss various directory implementation methods. [marks 8]

Earning:   Approval pending.