Download Semester 2 2012/2013

UNIVERSITI TENAGA NASIONAL
College of Information Technology
BACHELOR OF INFORMATION TECHNOLOGY (HONS.)
BACHELOR OF COMPUTER SCIENCE (HONS.)
FINAL EXAMINATION
SEMESTER II 2012/2013
OPERATING SYSTEM CONCEPTS
(CSNB224)
January 2013
Time allowed: 2 hours 30 minutes + 10 minutes for reading
INSTRUCTIONS TO CANDIDATES
1.
The total marks for this exam is 100 marks.
2.
There are THREE (3) SECTIONS to this paper; Section A, Section B and Section C.
3.
Answer ALL questions in the answer booklet provided.
DO NOT OPEN THIS QUESTION PAPER UNTIL YOU ARE INSTRUCTED TO DO SO
THIS QUESTION PAPER CONSISTS OF 9 PRINTED PAGES INCLUDING THIS PAGE
Page 1 of 9
SECTION A: TRUE / FALSE (10 QUESTIONS, 10 MARKS)
Instruction: Indicate whether each of the following statements is TRUE or
FALSE.
1.
The ability to evolve is one of the objectives of the operating system.
2.
In a uniprogramming system, processor must wait for the input/output
instruction to complete before it can execute the next program.
3.
A two-state process model consists of Not Running and Running states.
4.
In the Five-State Process Model, Running  Exit represents a valid state
transition.
5.
The Process Control Block refers to the binary form of the program code.
6.
The basic thread operation related to the change in thread state that occurs
when a thread needs to wait for an event is referred to as the spawn operation.
7.
Multiple threads may be created and executed within a single process.
8.
An echo procedure running on a multiprocessor system can produce erroneous
output if access to the echo procedure is unsynchronized.
9.
Concurrency issues are a concern on multiprocessor systems, but do not
impact uniprocessor systems.
10.
In a uniprocessor system, mutual exclusion can be guaranteed by disabling
interrupts.
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Operating System Concepts
SECTIOB B: FILL IN THE BLANKS (10 QUESTIONS, 10 MARKS)
Instruction: Fill in the blanks with the corresponding letters designating the
correct answer. One term only can be used once.
A. Process
G. Critical Section
M. Deadlock
B. Blocked/Suspend
H. Competition
N. Blocked  Running
C. Four
I. Application software
O. Trace
D. Kernel
J. Ready/Suspend
P. Two
E. Running  Exit
K. Three
Q. Communication
F. Critical Resource
L. Timer
R. System Software
1.
Operating system is one example of ________.
2.
________ contains the most frequently used functions in the operating system.
3.
A ________is used to prevent a single job from monopolizing the system.
4.
________ is a program in execution.
5.
We can characterize the behavior of an individual process by listing the
sequence of instructions that execute for that process and this listing is referred
to as a ________ of the process.
6.
Transition ________ happens when currently running process is completed or
aborts.
7.
________ is the state in which a process is in secondary memory and awaiting
an event.
8.
In order to implement mutual exclusion on a resource for competing
processes, only one program at a time should be allowed in the ________ of
the program.
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Operating System Concepts
9.
The relationship between processes that are directly aware of each other is via
________.
10.
There are ________ types of control problems for the processes that are
indirectly aware of each other.
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Operating System Concepts
SECTION C: STRUCTURED QUESTIONS (16 QUESTIONS, 80 MARKS)
Instruction: Please answer the following questions as concisely as possible.
Question 1
There are four necessary conditions to be satisfied before a deadlock can take place.
The conditions are mutual exclusion, hold and wait, no pre-emption and circular wait.
Briefly explain each of these conditions.
[6 marks]
Question 2
What does it mean by selection function and decision mode?
[4 marks]
Question 3
Explain the selection function and the decision mode for each of the scheduling
algorithms below:
(a)
First Come First Serve
[2 marks]
(b)
Shortest Process Next
[2 marks]
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Operating System Concepts
Question 4
The following table shows a set of 4 processes with their arrival time and burst time:
Process
Arrival time
Service Time
A
0
8
B
2
5
C
3
4
D
5
6
Draw the scheduling diagram and find the average waiting time for the processes
above using the scheduling algorithm below:
(a)
Shortest Remaining Time
[3 marks]
(b)
Round Robin (time quantum = 2ms)
[3 marks]
(c)
Highest Response Ratio Next (HRRN)
[3 marks]
Question 5
Feedback scheduling uses priority queue mechanism. Explain how scheduling is
being done using priority queues. Use a diagram to help you with your explanation.
[3 marks]
Question 6
In partitioning technique, the memory will be partitioned either in equal sized
partitions or unequal sized partitions. Briefly describe TWO (2) difficulties in equal
size partition.
[4 marks]
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Question 7
What is compaction? Explain your answer in terms of what compaction does and why
it is needed.
[3 marks]
Question 8
Consider a system with 1MB of memory being partitioned using the buddy system.
Draw a diagram showing the allocation of memory after each of the following
requests have been granted:
Request A: 70K; Request B: 120K; Request C: 80K; Request D: 60K;
Request E: 70K; Return D; Return C; Return E; Request F: 130K; Return
A ; Request G: 270K; Return F; Return G; Return B;
[7 marks]
Question 9
Briefly define the following terms:
(a)
Present bit
[2 marks]
(b)
Modify bit
[2 marks]
(c)
Segment Fault
[2 marks]
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Operating System Concepts
Question 10
(a)
What does replacement policy mean?
[2 marks]
(b)
Given below is the references made to the following pages by a program:
0, 2, 4, 1, 5, 1, 4, 3, 0, 3, 1
Show the successive pages residing in the three frames using replacement
policy below. Also, state how many page faults will occur for each of the
replacement policies.
(i)
FIFO replacement
[3 marks]
(ii)
LRU replacement
[3 marks]
(iii)
Optimal replacement
[3 marks]
Question 11
Explain why the performance of I/O operations is improved when using a double
buffer technique as compared to a single buffer technique.
[2 marks]
Question 12
Reading and writing data to disk involves seek time, rotational delay and access time.
Explain about each of these types of delays.
[3 marks]
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Question 13
The following figure shows the disk track request.
112, 237, 198, 180, 163, 211, 124
Assume that the last request is at track 150 and the head is moving towards track 0.
Perform an analysis and find out the average seek length for each of the disk
scheduling algorithms below:
(a)
Shortest Service Time First
[3 marks]
(b)
SCAN
[3 marks]
Question 14
Explain any THREE (3) functions that can be performed on a file.
[6 marks]
Question 15
List any THREE (3) criteria used when choosing an appropriate file organization
technique.
[3 marks]
Question 16
Space is allocated to a file or disk using preallocation or dynamic allocation
techniques. Describe about these two types of allocation techniques.
[3 mark]
---End of Questions---
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