Dibrugarh University 2009 B.Sc Information Technology Operating System - Question Paper

4 SEM IT two OS

2009

(June)

OPERATING SYSTEM

Paper:4.2

Full Marks:75

Time:3 hours

Answer ques. Nos. one and 2,and any 6 from the rest


1. ans in brief:

(a) What is a Process? [Marks 1]

(b) describe Spooling. [Marks 1]

(c) Why threads are essential for Operating
System? [Marks 1]

(d) describe Semaphore. [Marks 1]

(e) What is Thrashing? [Marks 1]

(f) What is Batch Processing? [Marks 1]

(g) What is a Boot Block? [Marks 1]

2. (a) What is the use of device switch
pointer? [Marks 2]

(b) What is the use of Compaction? [Marks 2]

(c) Compare ranging from time sharing and real
time operating system. [Marks 3]

(d) discuss how operating system manages
virtual memory concept. [Marks 3]

(e) Compare ranging from logical and physical
address space [Marks 2]

(f) What is a Process Control Block? [Marks 2]

3. Why system calls are required? discuss in
brief various structures of an operating
system. [Marks 4+5=9]

4. discuss the 1st come 1st serve scheduling
algorithm.

4 jobs A,B,C and D of duration four sec,
three sec,2 sec and one sec are coming in order. If
FCFS algorithm is employed, what is the
avg. turn-around time? [Marks 4+5=9]

5. elaborate various attributes of a file?
discuss in brief the methods for free space
management. [Marks 3+6=9]

6. What is a critical part problem? discuss
how deadlocks are detected and write the
points for recovery from the deadlock. [Marks 3+3+3=9]

7. discuss program controlled I/O. How does
program controlled I/O differ from interrupt
controlled I/O? discuss. [Marks 5+4=9]

8. What is disc scheduling? elaborate the
different disc scheduling algorithms?

The head of a moving head disc system with
100 tracks 0,1,2,...,99 is correctly
servicing a request at track 20. When this
request is being processed, request involving
tracks 15,30,10,45,55,35,5,95,85 arrive
in that order. What is the total head
movement needed to satisfy these requests
for the subsequent disc scheduling algorithms? [Marks 2+1+3+3=9]

(a) Shortest seek time 1st scheduling

(b) Scan scheduling

9. discuss the concept of Direct Memory
Access. elaborate device drivers? define
the role of device control block. [Marks 5+2+2=9]

10. Write short notes on any three: [Marks 3*3=9]

(a) System threats

(b) Demand paging

(c) Disk formatting

(d) Directory structure

Earning:   Approval pending.