Operating System PU Spring 2023 question paper

• a) Define operating system. Explain the fundamental differences between monolithic and layered structure of operating system.
• b) For what purpose semaphores are used? Give solution to producer- consumer problem using semaphores.

• a) Define PCB. How do processes transition between different states and what triggers these transitions? Illustrate with neat diagram.
• b) What are different types of kernels? Explain each in detail. q

• a) Consider the following set of processes with the length of the CPU burst given in milliseconds. Construct the Gantt chart and calculate average waiting time and turnaround time. Also explain which one is the best algorithm. a a ee [| =~ [| 2 | « [ #
• i) HRRN
• ii) RR (Quantum = Ims)
• iii) Priority Scheduling (1 higher priority)
• iv) Shortest Job First (pre-emptive)
• b) Examine the role of virtual memory. How does the Operating system map virtual address to physical address? Explain with example. Mae nl Serer

• a) Consider the following page reference strings: 9, 3, 4, 5, 3,9, 6, 7. 3.9, 3, 4, 8, 7, 4, 3,9, 3, 4, 7. How many page faults would occur for each of the following page replacement algorithms assuming 3 pages a frame? In each case calculate fault ratio.
• i) Second Chance page replacement
• ii) LRU page replacement
• iii) FIFO page replacement
• b) Define context switching Explain context switching by demonstrating a diagram that show how CPU switches from one process to another.

• a) Given a disk drive with 400 cylinders. The driver is currently servinga request at cylinder 162 and previous request was at cylinder 128. The queue of pending request in FIFO order is: 90, 150, 386, 94, 187, 48, 278, 202, 188, and 135. Starting from the current head position what is the total distance in cylinders that the disk to satisfy all the pending request for each of the following disk scheduling algorithms?
• v) FCFS _ vii) SCAN viii)C-Look
• b) How file naming is done? Discuss different file allocation methods.

• a) What are advantages of distributed system? Discuss RPC technique in Distributed System.
• b) How process management is done in UNIX or Linux? Explain. Why is Linux considered more secured then other operating system?

Write short notes on: (Any two) 2x5

• a) DMA.
• b) Windows 2000.
• c) The Shell. 2