University of Delhi 2011-2nd Sem Post Graduate Diploma Computer Application Pgdca- -cs-2.1 operating system - Question Paper
This question paper contains 6 printed page s. J
PGDCA / II Sem.
A
Paper-CS-2.1 OPERATING SYSTEM (Admissions of 1998 and onwards)
Maximum Marks: 100
Time: 3 Hours
(Write your Roll No. on the lop immediately on receipt of this question paper.)
Attempt all questions. Parts of a question should be answered together.
\ I- (a) (b)
(c)
What are the major functions of an operating system with respect to file management ? 3
Whafafe privileged instructions1 ? In which mode of the operating system are they .executed ? Justify your answer. 2+2
- - Vi;'
Describe the action taken ' by( ah operating system to switch context between Kernel level threads. 3
(d) What is a process ? How is it different from a program ? What are the different states of a process and the cause of transition from one state into another ? 1+1+3
(e) Distinguish between asynchronous and deferred cancellation of threads. 3
(f) Which of the following instruction are privileged ? 1
(i) Set value of timer
(ii) Clear memory
(iii) Turn off interrupts
(iv) Read the clock
2. (a) Differentiate between the following : 6
(i) Long-term and short-term scheduler
(ii) Preemptive and Non-preemptive scheduling
/
(b) Is it necessary that a time sharing system must have multiprogramming ? 2
(c) Describe the action taken by Kernel to context switch . 5
(i) Among threads
(ii) Among processes
(d) What are the advantages of acyclic graph directory ? 2
(e) What is multilevel paging ? How is it implemented ? Is it beneficial to have different levels of paging? 1+1+2
(f) In what situations would using memory as a RAM DISR be more useful than using it as cache? 2
3. (a) List the costs and benefits of implementing virtual memory. Under what conditions the costs can exceed benefits ? 5
(b) The concurrent processes Pi and P2 execute the following code segments in an uniprocessor environment.
Pi : v = v + 1
p2 : v = v - 1
Where v is a shared variable? What would be the problem of such concurrent execution ? 5
(c) What is round-robin scheduling ? Which of the following operating system use round-robin scheduling: 2+1+2
(i) Real time O/S
(ii) Time-shared operating system ?
What is context switch of round-robin scheduling ?
(d) What is Translation Look-aside Buffer (TLB) ? How the logical to physical address translation is done in both paging and TLB? 1+2+2
4. (a) Suppose that the following processes arrive for execution at the time indicated :
Process. Burst Time Arrival Time
Po '5 0
P, 4 1
P2 3 1
P3 5 2
P5 3 3
(i) Draw Gantt chans illustrating; the execution of these processes using FCFS. SJF. RR (time quantum = 2). 3
(ii) What is the waiting time for process Po, P2 in each scheduling algorithms? 2
(b) Specify features of Kernel and user mode routines regarding windows NT system. 3
(c) Discuss in detail various components of windows subsystem with diagram. 6
(d) Differentiate between the following ; 2x2
(i) Rights and Privileges
\ (ii) Swapping and Overlays
(c) Write short notes on : 2x3
(i) Handheld Systems
(ii) Command Interpreter
(iii) Swapper
5. (a) Describe the actions an operating system must take when page fault interrupt occurs. 5
(b) The producer-consumer algorithm for bounded buffer allows only n-\ buffers to be full at any time. Why ? 2
(c) Discuss, the different ,protocols supported by WINDOWS NT. 5
(d) What are differences between an interrupt and exception ? When is an exception generated ? Give suitable examples. 2+1+1
1756 6 200
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