IPU BCA Semester 5: Operating Systems (End Term Examination) - Dec 2014

END TERM EXAMINATION

FIFTH SEMESTER [BCA  2014]

Operating System

Paper Code : BCA- 301

Time : 3 Hours Maximum Marks:75

Note: Attempt any five questions. Question 1 is compulsory. Select one question from each section.

Question 1: Explain the following:

(5 x 5 = 25 marks)

(a) Explain multi programming and multi tasking systems.
(b) Explain logical versus physical address space.
 (c) List the differences between preemptive and non-preemptive scheduling.
 (d) Explain bit-interleaved parity organization and block-interleaved parity organization.
 (e) Explain logical and physical file system.

Section 1

Question 2:

(a) Discuss various types of fragmentation and memory allocation strategies.    (7.5)
(b) Explain the concept of thrashing.      (5)

  
Question 3:

(a) What is page replacement? What is its importance? Explain Least Recently Used (LRU) Replacement algorithm.                        (7.5)

(b) The following reference string (access sequence) is given:

0, 7, 1, 4, 3, 8, 1, 4, 3, 9, 1, 4,3, 2, 7, 5, 6

Find the number of page faults for a main memory susbsystem that has 4 frames and
uses LRU page replacement policy for on demanding paging.                               (5)

Section 2

Question 4:

(a) Consider the following set of processes with length of CPU burst times (given in milliseconds and arrival time as specified):

(5)

Process	Arrival Time	Burst Time
P1	0	7
P2	1	4
P3	2	8
P4	3	5

(b) Discuss Round robin scheduling algorithm and Priority Scheduling algorithm.      (7.5)


Question 5:

(a) What is semaphore? Describe the Readers-Writers problems.                         (7.5)

(b) What is the critical section problem? What are the three requirements that must be satisfied by a good solution to the critical section problem?                                                      (5)

Section 3

Question 6:

(a) Discuss Banker's algorithm in detail.                                                (7.5)

(b) Discuss Resource Allocation Graph Algorithm in detail.                    (5)


Question 7:

(a) Discuss various types of disk scheduling techniques.                         (7.5)

(b) Explain the concept of buffering.                                                        (5)

Section 4

Question 8:

(a) Explain directory structure of file system.                                              (7.5)

(b) Discuss general model of file system.                                                    (5)


Question 9:

(a) What are the different approaches to user authentication?                      (5)

(b) Explain the various types of threats to systems security.                        (7.5)