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Comp 220: Operating Systems Question Paper

Comp 220: Operating Systems

Course:(Bsc) In Computer Science

Institution: Kabarak University question papers

Exam Year:2013

KABARAK UNIVERSITY

UNIVERSITY EXAMINATIONS
2012/2013 ACADEMIC YEAR
FOR THE DEGREE OF (BSC) IN COMPUTER SCIENCE

COMP 220: OPERATING SYSTEMS
DAY: FRIDAY

DATE: 12/04/2013
TIME: 9.00 – 10.00 A.M.
STREAM: Y2S2
INSTRUCTIONS:

? ANSWER QUESTION ONE AND ANY OTHER TWO

Question one:- 30 marks

a). (i) What is Deadlock? Explain concept of critical region and Deadlock handling

(2 marks)
(ii) A system is composed of four processes, p1 through p4, and three types of consumable

resources, R1 through R3. There is one unit each of R1 and R3 available.
P1 requests a unit of R1 and a unit of R3.
P2 produces a unit of R1 and a unit of R3 and requests one unit of R2.
P3 requests a unit of R1 and a unit of R3.
P4 produces a unit of R2 and requests one unit of R3.

Show the consumable resource graph to represent the system state. Which, if any, of the

processes are deadlocked in this state?

(4 marks)

b). Describe the process states and functions involved in the transition of processes from one state to

another. Use a diagram to demonstrate your answer

(3marks)

c) State four benefits of threads

(2 marks)

d). Explain the meaning of the following terms
i.
Turnaround time

(1 mark)
ii.
Swapping

( 1 mark)

iii.
Blocked list

(1 mark)

e).Discuss the four main types of operating system stating clearly where they are used

(3 marks)
.
f). Explain context switching and under what circumstances does it take place.
(3 marks)

g). With the aid of a neat diagram, state and explain different process states
(2 marks)

h). State and explain different operating system services.

(3 marks)

i). A process enters a blocked state when it is waiting for an event to occur.name several events that
might cause a process to enter the blocked state.

(2 marks)

j). Explain in details three methods of recovering from a deadlock
(3 marks)

Question two:-20 Marks

a) Explain the working of monolithic operating systems and state its strengths.(6 marks)

b) Differentiate between multitasking and multiprogramming

(4 marks)

c) Differentiate between Preemptive and Non preemptive scheduling
(4 marks)

d) Consider a multi-level feedback queue in a single-CPU system. The first level (queue 0) is
given a quantum of 8 ms, the second one a quantum of 16 ms, the third is scheduled FCFS.
Assume jobs arrive all at time zero with the following job times (in ms): 4, 7, 12, 20, 25 and
30. Show the Gantt chart for this system and compute the average waiting and turnaround
time.

(6 marks)

Question three:-20 Marks

a) Explain the main functions of the Operating System
(4 marks)

b) What is process spawning?

(2 marks)

c) Define Process control block

(1 mark)

d) List six information items that can PCB contain.

(3 marks)

e) A key feature of any operating system is the system call.

i).What is a system call?

(2 marks)

ii).What is the difference between an Interrupt and a System Call?
(2 marks)
f). Differentiate between turnaround time and time slice

(4 marks)

Question four 20 marks

a) Define a semaphore. Hence Explain how it helps the processes to synchronize their activity

(2 marks)
b) Explain the following scheduling algorithms:-

i).FCFS

ii).SRT

iii).Round Robin

iv).Priority scheduling

(7 marks)
c) Differentiate between Preemptive and Non preemptive scheduling

(4 marks)
d) What is meant by paging? Discuss Demand Paging in details

(3 marks)

e) Discuss with a suitable diagram the microkernel operating systems structure
(4 marks)

Comp 220: Operating Systems Question Paper

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