Cc Pages: 3
02000CS204052001
Reg No.: Name:
APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY

Fourth semester B.Tech examinations (S), September 2020

Course Code: CS204
Course Name: OPERATING SYSTEMS (CS)

Max. Marks: 100 Duration: 3 Hours
PART A
Answer all questions. Each carries 3 marks.

1 Write the differences between time sharing systems and multiprogramming 3
systems.

2 What is the use of Process Control Block (PCB) in operating system? 3

3 How many times “Welcome” will be printed for the following code? 3
void main() { fork(); fork(); fork(); printf (““Welcome\n’’);}

4 In a multiprocessor computer system bitmap is used for keeping track of the status 3

8 processors in the system. How many bits will be there in the bitmap? If
2106055010, processor3 and processorS are currently allocated write the bitmap.
PART 8
Answer any two questions. Each carries 9 marks.
5 2) शुं do you understand by the layered structure of an Operating System? Point 5
out its advantages and disadvantages.
b) How the long term scheduler directly affects the system performance?

6 9) Write the operations taking place during the booting of a system.

b) In a message passing system how the send() / receive() operations and
communication link is implemented in case of — direct and _ indirect
communication?

7 2) Mention the purpose of system call. How the parameter passing takes place in 5
system call.

0) What 15 process cooperation? What are the benefits of process cooperation? 4
PART C
Answer all questions. Each carries 3 marks.

What is meant by critical section? What is critical section problem? 3

9 Illustrate how semaphores can be used as a synchronisation mechanism? 3

10 What do you understand by starvation in operating systems? How starvation can 3
be solved in priority scheduling?

11 Write the four situations under which CPU scheduling decisions take place. 3

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