BCA 4th Semester
Operating System Board Question Paper 2020

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

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

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

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.

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

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

Write CPU scheduling criteria. For the processes listed in following table, draw 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 (quantum = 1 sec.)

Define the term 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 previous request was at cylinder 25.
The queue of pending request, in FIFO order is: 86, 70, 13, 74, 48, 9, 22, 50, 30 Starting from the current head position, what is total distance (in cylinders) that the disk arm moves to satisfy all pending request for each of following disk scheduling algorithms?
a) FCFS
b) SSTF
c) SCAN
d) LOOK

What is clock synchronization? Explain how physical clock synchronize by Berkeley algorithm and logical clock synchronize by Lamport's algorithm with suitable example.