Group B

2. What is an operating system? Explain the functions of an operating system.

3. Define the term semaphore. How does semaphore help in the dining philosopher problem?

4. A system has two processes and three resources. Each process needs a maximum of two resources. Is deadlock possible? Explain with answer.

5. Suppose a new process in a system arrives at an average of six processes per minute and each such process requires an average of 8 seconds of service time. Estimate the fraction of time the CPU is busy in a system with a single processor.

6. Given references to the following pages by a program: 0, 9, 0, 1, 8, 1, 8, 7, 8, 7, 1, 2, 8, 2, 7, 8, 2, 3, 8, 3. How many page faults will occur if the program has three page frames for each of the following algorithms? a) FIFO b) LRU

7. What is a file? Explain how an access control matrix provides resource protection that may access a process.

8. What do you mean by one-time password in authentication? How do worms differ from viruses?

Group C

9. Write CPU scheduling criteria. For the processes listed in the following table, draw a Gantt chart illustrating their execution and calculate average waiting time and turnaround time using: a) First Come First Serve b) Shortest Remaining Time Next c) Priority d) Round Robin

Processes	Arrival Time	Burst Time (sec.)	Priority
A	0.00	7	3
B	2.01	7	1
C	3.01	2	4
D	3.02	2	2

10. Define the terms seek time and rotational delay in disk scheduling. Suppose that a disk has 100 cylinders, numbered 0 to 99. The drive is currently serving a request at cylinder 43 and the previous request was at cylinder 25. The queue of pending requests, in FIFO order is: 86, 70, 13, 74, 48, 9, 22, 50, 30. Starting from the current head position, what is the total distance (in cylinders) that the disk arm moves to satisfy all pending requests for each of the following disk scheduling algorithms? a) FCFS b) SSTF c) SCAN d) LOOK

11. What is clock synchronization? Explain how a physical clock synchronizes via the Berkeley algorithm and a logical clock synchronizes via Lamport's algorithm with a suitable example.

2020 Board Question Paper

2020 Board Question Paper