Hall Ticket No Question Paper Code: ACS007
INSTITUTE OF AERONAUTICAL ENGINEERING
(Autonomous)
B.Tech IV Semester End Examinations (Supplementary) July, 2018
Regulation: IARE R16
OPERATING SYSTEMS
Time: 3 Hours (Common to CSE IT) Max Marks: 70
Answer ONE Question from each Unit
All Questions Carry Equal Marks
All parts of the question must be answered in one place only
UNIT I
1. What is a system call? Explain how it is been implemented by passing the parameters.
What are the differences between kernel mode and user mode?
2. Explain the differences between multiprogramming, multi-tasking and time-sharing systems?

Explain the system architectures of single, multi processors and clustered systems.
UNIT II
3. What is a thread? What is a process? Describe how to create each of these in detail.
What is the producer consumer problem? Give an example of its occurrence in operating systems.

4. Can any of the two scheduling schemes First Come First Serve and Shortest Job First result in
starvation? If so, how might you fix this.
Assume you have the following jobs to execute with one processor, with the jobs arriving in the
order listed as shown in Table 1.
Table 1
Job Burst time Priority
P1 8 4
P2 6 1
P3 9 2
P4 1 2
P5 3 3
Calculate average waiting time and turnaround time for the following:
i. First Come First Served method
ii. Shortest Job First method
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UNIT III
5. Differentiate between internal and external fragmentation and which one occurs in paging scheme.

What is FIFO page replacement algorithm? Enumerate the FIFO with the given reference string
as w dcbadcedcbae with 3 and 4 frames.
6. What is thrashing? How it is been detected? How might one recover from it once detected?

Consider a logical address space of eight 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 many bits are there in the physical address?
UNIT IV
7. Describe the attributes of the file and its various operations involved in it.
Calculate the total time taken by the FCFS, SCAN and LOOK disk scheduling algorithms on a
queue 23, 89, 132, 42, 187 in which there are 200 cylinders numbered from 0 199 and the disk
head starts at number 100.
8. Compare and contrast the methods of direct access and sequential access in file systems.
Base-limit MMUs can support swapping. What is swapping? Can swapping permit an application
requiring 16MB memory to run on a machine with 8MB of RAM? How does the Linux support
the swap?
UNIT V
9. Explain briefly resource allocation graph with examples?
Why do you need to provide protection to the system? Explain how access matrix can be used
for the purpose?
10. What is deadlock? What is starvation? How do they differ from each other? What are the four
conditions required for deadlock to occur?
Assume that there are three resources, and C. There are 4 processes P0 to P3. At T0 we
have the following snapshot of the system as shown in Table 2. Is the system in a safe state?
Why or why not?
Table 2
Allocation Max Available
A B C A B C A B C
P0 1 0 1 2 1 1 2 1 1
P1 2 1 2 5 4 4
P2 3 0 0 3 1 1
P3 1 0 1 1 1 1
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