Punjab Technical University 2007 Bachelor of Computer Science (B Level) Operating Syseems,os - Question Paper

Operating Syseems
(B.Tech 4rd Semester, 2122)
Time: 03 Hours Max marks: 60
Instruction to candidates:
1) Section –A is compulsory.
2) Attempt any 4 ques. from section-B
3) Attempt any 2 ques. from section-C



part -A
Q1) (marks 10*2=20)


1 (a) What is the purpose of system calls ?
(b) describe process.
(c) What is non-preemptive scheduling ?
(d) What info is contained in PCB ?
(e) Is it possible to have a deadlock involving only 1 single process ? discuss your ans.
(f) Consider a logical address spalce of 8 pages of 1024 words each, mapped onto a physical
memory of 32 frames.
(i) How many bits are there in the logical address ?
(ii) How are bits are there in the physical address ?
(g) What is dynamic relocation ?
(h) What is thrashing ?
(i) discuss the concept of stable storage.
(j) discuss the worm as concern system threats.

Section-B Marks:5 every

2. define the action taken by a kernal to situation switch :
(a) Among threads.
(b) Among Processes.
3. What advantage is there in having various time-quantum sizes on various levels of a multilevel
queuing system ?
4. What is the meaning of the term busy waiting ? What other types of waiting is there ? Can busy waiting
be avoided altogether? discuss your ans.
5. discuss the use of semaphores for process synchronization.
6. Why and how are segmentation and paging sometimes combined into 1 scheme ?

Section-C Marks : 10 every

7. List 5 services given by an operating system. discuss how every provides convenience to the users.
discuss also in which cases it would be impossible for user-level programs to give these services.
8. explain different page replacement betrothal's. What is Balady's anomaly ?

Earning:   Approval pending.