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			 <![CDATA[ Operating System ]]> 
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			<![CDATA[ 



Total number of printed pages –
7
                                                                                   
B. Tech
BCSE
3305
Sixth / Eighth Semester
Examination – 2008
OPERATING
SYSTEM
Full Marks –
70
Time: 3
Hours
Answer Question No. 1 which is
compulsory and any five from the
rest.
The figures in
the right – hand margin indicate marks.

1.      
1. Answer the following questions:                                                                                                                                                                                                                       
2 × 10
(a)   
What are the differences between binary and general
semaphores?
(b)  
What are the essential goals of disk scheduling?
(c)   
What is the difference between deadlock prevention and deadlock
avoidance?
(d)  
When do page fault occurs?
(e)  
What are the advantages of storage interleaving?
(f)    
What is purpose of short – term – scheduler and long – term –
scheduler?
(g)   
Can a resource allocation graph have cycles without a deadlock
existing? If so state why and draw a sample graph; if no, state why not?
(h)  
What is the difference between trap and interrupt?
(i)     
Define the difference between preemptive and non – preemptive
scheduling.
(j)    
What are the basic functions of an operating system?
2.      
               
(a)   
What do you mean by process in a computer system? What are the
different process states?
Explain the
process life cycle in operating system.                                                                                                                                                                       
       5
(b)  
When do page fault occurs? Describe the actions taken by the
operating system, when a page fault occurs.                                                                                        
5

3.      
                 3.
(a)   
What resources are used when a thread is created? What two
advantages do threads have over multiple processes? What major disadvantages do
they have?          5
(b)  
Why paging is used? Which is the best page replacement algorithm
and Why? How much time is spent usually in each phases and why?                                           5

4.      
                
4.
(a)   
Explain the structure of a Process control Block. Explain how the
process is created when program is in execution?                                                                             
5

(b)  
Define deadlock. State four conditions of deadlock and explain
how each condition can be satisfied?             
                                                                                    
5

5.      
                5.
(a)   
When a resource is returned by a process calling a monitor, the
monitor gives priority to an end waiting process over a new requesting process?
Why?                        5
(b)  
What do you mean by inter  - process
communication mechanism associated with an Operating system? Discuss the
mechanism associated with fifo()?                      
5

6.      
                6.
(a)   
In a test of a new operating system,  the
ready queue scheduler uses FCFS. For a particular test, beginning at time zero,
the evolution of the ready queue is as follows:

Process                        Arrival time                                        Next CPU Burst
time

P0                                             0                                                                   
7

P1                                             0                                                                   
8

P2                                             1                                                                   
4             

P3                                             4                                                                   
6
It may be
assumed that P0 and P1 arrive just fractionally before time zero, but P0
arrives before P1. All times in the above table: arrival and burst time, are in
milliseconds. The next scheduling decision is made at time zero. What is the
average wait time?                                             
                                                                               
                                                5
(b)  
Give an example of a simple resource deadlock involving three
processes and three resources. Draw the appropriate resource allocation
graph.                                 5

7.      
                7.
(a)   
Consider the following reference string. Calculate the page fault
rates for the FIFO and LRU algorithms. Assume that the memory size is 4
frames.                            5

1, 2, 3, 4, 5, 3, 4, 1, 6, 7, 8, 7, 8, 9, 7, 8, 9, 5, 4, 5, 4,
2
(b)  
Why SSTF scheduling tends to fervor middle cylinder over the
innermost and outermost cylinder?                  
                                                                                    
5

8.      
                8.
(a)   
Suppose three concurrent processes, P1, P2 and P3, executing in a
machine with a single processor.
P1 contains
an instruction S1;
P2 contains
an instruction S2;
P3 contains
an instruction S3;
The three
processes use a busy waiting semaphore synch and wait()/single() code to ensure that both S2 and S3 execute
before S1.

Hence answer the followings:                                                                                                                                                                                                            
6
(i)                 
Which process or processes require that signal
(sync) be inserted appropriately?
(ii)               
If synch can be initially set to any integer
value, positive, negative or zero, what value must synch be
initialized to?
(iii)              
Write out the semaphore code that must be placed near S1 in P1 to
ensure that both S2 and S3 execute before S1. Include “S1;” in your answer.
(b)  
Explain the difference between internal fragmentation and
external
fragmentation.                                                                                                                             
4

                                                                              
 ]]> 
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		<pubDate>Sun, 03 Aug 2008 17:29:18 +0000</pubDate>
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		<title>
			 <![CDATA[ Sixth Sem Ques ]]> 
		</title>
		<description>
			<![CDATA[ * [[Computer Networks]] ]]> 
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			http://kulkant.atwiki.com/page/Sixth%20Sem%20Ques
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		<pubDate>Sun, 03 Aug 2008 17:17:12 +0000</pubDate>
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			 <![CDATA[ Photos ]]> 
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			<![CDATA[ 

            Bony

         Sukumar
 ]]> 
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		<pubDate>Sun, 03 Aug 2008 06:26:44 +0000</pubDate>
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		<title>
			 <![CDATA[ Computer Networks ]]> 
		</title>
		<description>
			<![CDATA[ B. Tech
BCSE 3306

'''Sixth / Eighth Semester Examination – 2008'''

'''COMPUTER NETWORKS'''

Full Marks – 70

Time: 3 Hours

Answer Question No. 1 which is compulsory and any five from the rest.
The figures in the right-hand margin indicate marks

1. Answer the following questions:							2 × 10

(a) Suppose the size of an uncompressed text message is q megabytes. How long does it take to download the file over a 32 kilobits.sec modem?

(b) What is the difference between simplex and half duplex transmission mode?

(c) Explain the difference between character stuffing and bit stuffing.

(d) State how connection less protocol differs from connection oriented protocol.

(e) Explain the meaning of the term protocol converter.

(f) Why does IPV6 allow fragmentation at the source only.

(g) Perform bit stuffing for the following sequence: 1101 1111 1101 1111 10101

(h) Explain the difference between connectionless unacknowledged service and connectionless acknowledged service.

(i) Define Nyquist singnaling rate.

(j) How many errors in a message can be corrected using LRC?

2. 

(a) What is the function of a null modem? Show the internal connections used within a null modem and explain the significance of each connection.			5

(b) Explain how clock synchronization can be achieved using:
	(i)  Bipolar encoding
	(ii) Differential Manchester encoding.                                                               5                     
											
3. 

(a) With the help of frame sequence diagram, explain how the following frames are handled in a Go-Back-N ARQ protocol:

(i)	A corrupted I – frame and

(ii)	A corrupted ACK – frame.                                           5

(b) Explain the principle of operation of CSMA / CD MAC used in LAN.		5

4. 

(a) Describe the structure of IP datagram and explain the function of each field in the context of the IP protocol.								5

(b) List the message types associated with the internet control message protocol (ICMP) and explain the various functions associated with the protocol.			5

5. 

(a) Sketch the header of a TCP segment. Explain the function of each field.		5
	
(b) Use Dijkstra algorithm to find the set of shortest path from node 4 to other nodes.
												5
			2
	2
	3	5
	          1	3
	1
	4

6. 

(a) Compute the CRC – 4 character for the following message using a “divisor” constant of 10011.										5
	
(b) The original three network types were LAN, MAN and WAN. Describe how they differs from one another.								5

7. 

(a) What is the drawback of PSK versus FSK modulation.				5
	
(b) How does frame relay differs from ATM.						5

8. 

Write short notes on any two:								5 × 2
	
(a) Guided media.
	
(b) Bluetooth
	
(c) Cryptography. ]]> 
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		<pubDate>Sat, 05 Jul 2008 06:04:42 +0000</pubDate>
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		<title>
			 <![CDATA[ CS ]]> 
		</title>
		<description>
			<![CDATA[ * [[Sixth Semester]] ]]> 
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			http://kulkant.atwiki.com/page/CS
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		<pubDate>Sat, 05 Jul 2008 05:35:25 +0000</pubDate>
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			 <![CDATA[ Questions ]]> 
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		<description>
			<![CDATA[ * [[CS]] ]]> 
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			http://kulkant.atwiki.com/page/Questions
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		<pubDate>Sat, 05 Jul 2008 05:33:34 +0000</pubDate>
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		<title>
			 <![CDATA[ New ]]> 
		</title>
		<description>
			<![CDATA[ * Now you can see the 6th semester CSC time table of OEC here in [[6th_sem_time_table]] ]]> 
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		<pubDate>Sat, 05 Jul 2008 05:32:31 +0000</pubDate>
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		<title>
			 <![CDATA[ About ]]> 
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		<description>
			<![CDATA[ 
This is my first website I ever made. I tried to put my feet on the world of
Web
For any suggestion please mail me at kulkant@gmail.com
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		<pubDate>Sat, 05 Jul 2008 04:53:18 +0000</pubDate>
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			<![CDATA[                                                                                             ==Welcome==

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