R09 - December, 2011 - Regular Examinations - Set - 2.

B. Tech III Year I Semester Examinations, December-2011
OPERATING SYSTEMS
(COMMON TO CSE, IT)
Time: 3 hours Max. Marks: 75
Answer any five questions
All questions carry equal marks
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1.a) Distinguish between the chart-server and peer-to-peer models of distributed systems
b) State and explain the various types of system cells in detail [7 8]
2.a) In some situations a change in the state of one process may cause a change in the state of another process. Describe all such situations
b) Compare and contrast the ECES and STE scheduling algorithms illustrate with Gantt chart whenever necessary. [7 8]
3.a) Define the instructions, test and set ( ) and swap ( )
b) Explain the implementation of mutual – exclusion with the above Instructions.
c) Explain the implementation of mutual-exclusion semaphores. [15]
4.a) What is demand paging and how is it implemented?
b) Explain LRU page replacement algorithm with a neat example.
c) State and explain thrashing. [15]
5.a) State and explain four conditions that are necessary for deadlocks to occur neat example.
b) What is safe state? Illustrate with a neat example. [15]
6.a) Describe the most common schemes foe defining the logical structure of a directory
b) State and explain the four approaches to free-space management. [7 8]
7.a) Consider the following disk queen with requests for I/O to blocks on cylinders 98,183,37,122,14,124,65,67 in that order, using FCFS algorithm of the disk head is initially at cylinder 53,find the total head movement in cylinders. Also provide the necessary diagram to show the head movement for the above queue.
b) What is DMA? With neat diagram explain the steps involved in a DMA transfer. [7 8]
8.a) Write short notes on :
i) Nature of viruses
ii) Type of viruses
iii) Anti-Virus approaches
b) What is access matrix? How is it implemented? [15]
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