Operating Systems — DU B. Voc – Software Development Previous Year Question Papers

1 a) What is an Operating System? Explain Time Sharing and Real Time Operating System. b) Consider the following page reference string 7 ,0, 1,2,0,3,0,4,1 ,2,0,3,2, 1,7 ,0, 1,7,0,2. How many page faults would occur for FIFO page replacement algorithm, assuming three frames? c) Describe various file access methods. d) What is meant by Locality of Reference? e) Explain various states of a process with the help of a suitable diagram. l1 What is a Semaphore? Describe the operations for accessing semaphores. 4 C) Fill in the Blanks : i. Each process maintains a ii. Shortest Job First Scheduling is a scheduling. to store its attributes. version of h) True/False 11. Pages are of fixed size and segments are olvariable size. (T,/F) The medium-tenn scheduler only runs in times of high resource contention, as when physical memory is full. (T/F) i) Choose the correct option : Hard real time operating system has soft real time operating system. a) equal b) more c) less d) none of the mentioned jitter than a 11. ln Unix, which system call creates the new process? a) create b) fork c) new d) none of the mentioned 2 a) What are the different file allocation methods. Explain the linked allocation of file implementation with it's merits and demerits. b) What are the five major activities of an operating system with regard to process management? 3 a) Consider the following set ofprocesses. Find the average waiting time using Gantt chart for : (i) SJF algorithm (ii) Priorityschedulingalgorithm gurst time Priority p1 5 The grocess has arrived in the order p2. p1, p4, p3 aad p5. b) Write short notes on each of the flollowing: i) Working set model ii) Fragmentation 4 a) Differentiate between : i)Paging and Segmentation ii)Multiprogramming and Multitasking operating systems b) How deadlock can be prevented? 5 a) Explain Banker's deadlock-avoidance algorithm rvith an example. b) Consider a logical address space of64 pages with 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? 6 a) Wrat is disk scheduling? Explain different disk scheduling algorithms. 5 b) '7 a) b) Consider the following page reference string: 1,2,3,4,2,1,5,6,2,1,2,3,7,6,1,2,6,5. Number of page frames are 4. Find out the number of page faults using the following page replacement algorithms Consider a paging hardware u.ith a TLB. Assume that the entire page table and all the pages are in the physical memory. It takes 10 milliseconds to search the TLB and 80 milliseconds to access the physical memory. If the TLB hit ratio is 0.6, calculate the effective memory access time (in milliseconds). Evaluating the maximum number of pages needed ifa system supports 16 bit address line and lK page size.