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December 2002

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Question Paper of CS-13 – Operating Systems of December 2002 from IGNOU

1. (a) Write and explain one of the deadlock detection algorithms and evaluate its performance.

(b) Explain the logic of Dekker�s solution to the mutual-exclusion problem and also discuss whether it is suitable to be implemented in a multiprocessors system with shared memory.

(c) Describe Belady�s anomaly and provide an example that illustrates anomalous behaviors of FIFO.

2 (a) Compare and contrast implicit tasking and Explicit tasking of the processes. Also highlight the advantages of Explicit tasking.

(b) The identified disadvantages of semaphores are
(i)Semaphores are unstructured
(ii) Semaphores do not support data abstraction.

3 (a) Write short notes on the following:
(i) Two-phase locking
(ii) Wait-die and Wound-wait
(iii)Busy waiting

(b) Compare and contrast Remote Procedure Call (RPC) With Message passing in Distributed O/S environment.

4 (a) Explain the difference between internal fragmentation and external fragmentation. Which one occurs in paging system? Also, explain through a diagram, the principle of address translation in paging scheme.

(b) What are PAGE MAP TABLE (PMT), MEMORY MAP TABLE (MMT) and FILE MAP TABLE (FMT)? Explain how they are associated in the management of virtual memory.

5 (a) Explain why shared-bus multiprocessors are generally regarded as having limited scalability.

(b) State and discuss the differences in resource management requirements between Uniprocessor and Multiprocessor operating systems.

(c) What is disk caching? What are its advantages?

6 Wrote short notes on:
(i) Bell-LaPadula Model
(ii) Chaining and Indexing allocation strategies of disk space
(iii)Rivest, Shamir, Adelman (RSA) algorithm

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June, 2002

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Question Paper of CS-13 – Operating Systems of June 2002 from IGNOU

Note :The candidates are required to attempt four questions in all.
Q. No.one is compulsory and carries 30 marks.
Q. Nos. two to six carry 15 marks each.

1(a) Explain the drawbacks of Busy-Wait implementation of semaphores. How can we overcome these by using queuing implementation of semaphores? Discuss.

(b) Explain the Rivest, Shamir, Adelman (RSA) public key algorithm.

(c) Explain the anatomy of Disk Address Transaction.

2(a) What is the difference between a program and a process? Explain the four general categories of process states with the help of process state-transition diagram.

(b) Explain the following scheduling algorithms:
(i) Shortest Remaining Time Next (STRN) scheduling
(ii) Time slice scheduling
(iii) Event driven scheduling
(iv) Multiple-level queues scheduling

3(a) Discuss various machine level implementation of mutual exclusions in general and of semaphores in particular. Also discuss suitability and efficiency of these algorithms.

(b) Explain how a monitor can be implemented with semaphores.

4(a) Explain the following common algorithms for selection of a free area of memory for creation of a partition:
(i) First fit
(ii) Best fit
(iii) Worst fit

(b) Write short notes on:
(i) Memory Compaction
(ii) Hierarchical Address Translation Table

5. (a) Explain the following 3 levels of device abstraction and disk storage addressing techniques which are commonly identifiable in implementation of the file management system :
(i) File Relative logical addressing
(ii) Volume Relative logical addressing
(iii) Drive Relative physical addressing

(b) Explain the Biometric authentication mechanism.

6 (a) Explain the Bus oriented systems and Multistage switch based system architectures for multiprocessor interconnections.

(b)Explain the Ricart and Agrawala�s algorithm for distributed processing.

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Dec, 2001

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Question Paper of CS-13 – Operating Systems of Dec 2001 from IGNOU

Note :The candidates are required to attempt four questions in all.
Q. No.one is compulsory and carries 30 marks.
Q. Nos. two to six carry 15 marks each.

1(a) Write an algorithm/program using the file system calls (open, creat, read, write, break, close, unlink) That determines the lenght of a file without using a loop in the code.

(b) Explain the following 3 primary forms of explicit interprocess interaction:
(1) Interprocess synchronization
(2) Interprocess signaling
(3) Interprocesscommunication.

Also discuss the need for Interprocess synchronization.

(c) What is Translation lookaside buffer (TLB)? Describe the functions of TLB in a paging system and also discuss the issues and operations involved in TLB management by the operating system.
2 (a) Explain how �threads� approch improves performance of operating system.

(b) �Any syncronization problem that can be solved with sempaphores can be solved with messages and vice versa�. Explain the reasoning you need to come up with your answer.

3 (a) Discuss the Multiprocessor classification based on Flynn�s caheme. Also mention the advantages of multiprocessor.

(b) Explain the merits and demerits of distributed processing.

4(a) Compare contiguous allocation and Non contiguous allocation with respect to following measures:
(i) Wasted memory
(ii) Time complexity
(iii) Memory Access overhead.

(b) Explain the role of file map table (FMT) in the management of virtual memory.

5 (a) Explain the following with respect to the Disk space management :
(1) Chaining
(2) Indexing.

(b) Explain the Saltzer and Schroeder�s general design principles for protection mechanisms.

6 Write short notes on:
(1) Artifact based Authentication
(2) Hyper cubes
(3) Remote procedure Calls
(4) Distributed shared memory.

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JUNE 2001

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Question Paper of CS-13 – Operating Systems of June 2001 from IGNOU

1. (i) Write an algorithm for bounded buffer producer/consumer problem using monitor. Also describe the problem and algorithm in detail.

(ii) Discuss in detail the distribution of control and the degree o functional specification of the individual processing elements in the three major classes of multiprocessor operating system.

(iii) A processor references five page A ,B,C,D and E in the following order :

A, B,C,D,A,E,B,C,E,D
Read more…

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JAN 2001

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Question Paper of CS-13 – Operating Systems of Jan 2001 from IGNOU

Time : 3 Hours
Max. Marks : 75

Note: Question 1 is compulsory.
Answer any three from the rest.

1. (a) Write an algorithm for implementing Dining philosopher problem using semaphores. Also describe the problems and the algorithm in detail.

(b) What is the time stamping scheme of distributed system for mutual exclusion? Explain the functioning of the scheme through a diagram.

(c) Describe the algorithm proposed by Ricart and Agrawal for distributed mutual exclusion. Also distinguish between this algorithm and Lamport;’s algorithm on the following lines:
- Correctness of the algorithm
- Deadlock
- Communication cost Read more…

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DEC 2000

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Question Paper of CS-13 – Operating Systems of Dec 2000 from IGNOU

Time : 3 Hours
Max. Marks : 75

Note: Question 1 is compulsory.
Answer any three from the rest.

1. (a) Write an algorithm that solves the readers/writers problem using monitors

(b) Devise an algorithm for Dead-lock detection, Discuss the operational aspects of this algorithm

(c) Discuss the common performance measures and optimization criteria that the schedulers use in attempting to maximize system performance. Read more…

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JUNE 2000

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Question Paper of CS-13 – Operating Systems of June 2000 from IGNOU

Time : 3 Hours
Max. Marks : 75

Note: Question 1 is compulsory.
Answer any three from the rest.

1. (a) Hierarchical directories are more complex to manage than flat files, but their advantages are considered to outweight their drawbacks by many system designers. Explain why.

(b) Design algorithms/functional specifications for the basic range of file-related system services given below :
(i) CREATE
(ii) SEEK
(iii) READ
(iv) WRITE

(c) Discuss the queuing implementation of Semaphores. The algorithm should be nearer to ‘C’ Language implementation Read more…

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JUNE 1999

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Question Paper of CS-13 – Operating Systems of June 1999 from IGNOU

Note: Question 1 is compulsory.
Answer any three from the rest.

1 (a). Explain First come, First served (FCFS) and Round Robin scheduling algorithms.

(b). Consider the following set of processes, with the length of the CPU burst time given in milliseconds:

Process Burst Time
P1 10
P2 29
P3 3
P4 7
P5 12 Read more…

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DEC 1997

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Question Paper of CS-13 – Operating Systems of Dec 1997 from IGNOU

Time : 3 Hours
Max. Marks : 75

Note: Question 1 is compulsory.
Answer any three from the rest.

1.
(a) Assume that in the system shown in the following figure, Process p1 does not won a disk drive and it requests two disk drives simultaneously. Illustrate that situation by means of the general resource graph and use the deadlock detection algorithm to evaluate the resulting system state.

(b) Discuss whether each of the following programming techniques and program action is good or bad with regard to the degree pf locality of page reference it is likely to exhibit. Explain your reasoning and where applicable, state roughly the number of distinct loci of activity (hot spots) that you expect the execution to generate.

(i) Sequential processing of one dimensional array Read more…

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JUNE 1998

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Question Paper of CS-13 – Operating Systems of June 1998 from IGNOU

Time : 3 Hours
Max. Marks : 75

Note: Question 1 is compulsory.
Answer any three from the rest.

1.
(a) Identify and discuss all operations and parameters that influence the effective memory access time in a virtual-memory system. Indicate the most significant changes that may be expected with future technological improvements, such as introduction of the secondary storage devices with access time one or more orders of magnitude faster than that of contemporary devices.

(b) A disk has 305 cylinders, four heads and 17 sectors of 512 bytes each per track. The disk is rotated at 3000 rpm and it has a moving head assembly with an average head positioning time of 30 ms. The peak date transfer rate that the drive can sustain is 4 mbps. Calculate the best and the worst case time needed to transfer 20 consecutive and 20 randomly distributed blocks (sectors)from such a disk. Indicate the dominant factors in determining the transfer times and the variability between the best case and the worst case figures.

(c) Give several reasons why the study of concurrency is appropriate in OS design Read more…

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