Universiti Malaysia PAHANG Engineering . Technology Creativity

FACULTY OF COMPUTER SYSTEMS & SOFTWARE ENGINEERING

FINAL EXAMINATION

COURSE : OPERATING SYSTEMS

COURSE CODE : BCN2053

LECTURER : IMRAN EDZEREIQ KAMARUDIN ZARINA DZOLKI{IFLI

DATE : 3 JANUARY 2014

DURATION : 3 HOURS

SESSION/SEMESTER : SESSION 2013/2014 SEMESTER I

PROGRAMME CODE : BCN/BCS/BCG

INSTRUCTIONS TO CANDIDATE:

1. This question paper consists of Four (4) questions. Answer ALL questions. 2. Write your answers in the answer booklet provided. 3. Answer EACH question on a new page. 4. All calculations and assumptions must be clearly shown. Calculator is allowed

EXAMINATION REQUIREMENTS:

NONE

DO NOT TURN THIS PAGE UNTIL YOU ARE TOLD TO DO SO

This examination paper consists of Six (6) printed pages including the front page.

CONFIDENTIAL

BCN/BCS/BCG/13141/BCN2053

[80 MARKS]

QUESTION 1 [20 Marks]

a) Explain the impact of the evolution of computer hardware and the accompanying evolution of operating systems software.

[4 Marks]

b) Explain the fundamental differences between interactive, batch, real-time, and embedded systems.

[8 Marks]

c) Given the following information in Table 1

Table 1

Job number Memory Requested Memory Block Memory Block Size Job 1 275K Block 1 300K

Job 600K Block 2 280K

Job 300K Block 400K

i. Using the first-fit algorithm, indicate which memory blocks are allocated to each of the

three arriving jobs. Investigate and calculate the internal fragmentation based on the allocation algorithm

[4 Marks] ii. Using the best-fit algorithm, indicate which memory blocks are allocated to each of the

three arriving jobs. Investigate and calculate the internal fragmentation based on the allocation algorithm

[4 Marks]

2

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QUESTION 2 [20 Marks]

a) Given that main memory is composed of two page frames for public use and that a program requests pages in the following order:

a, b, a, c, a, b, d, b, a, c, d

i. Using the FIFO page removal algorithm, illustrate a page trace analysis and compute

the failure and success ratios

[3 Marks]

ii. Using the LRU page removal algorithm, illustrate a page trace analysis and compute

the failure and success ratios

[3 Marks]

b) Compare internal fragmentation and external fragmentation. Explain the circumstances where one might be preferred over the other.

[5 Marks]

c) Suppose that a disk drive has 200 cylinders, numbered 0 to 199. The drive is currently serving a request at cylinder 170. The queue of pending request in FIFO order is:

98 183 37 122 14 124 65 67

Starting from the current head position, illustrate and calculate the total distance (in cylinders) that the disk arm moves to satisfy all the pending requests for each of the following disk-scheduling algorithms.

L SSTF

ii. SCAN (assuming arm movement towards the beginning of disk)

iii. C-SCAN (assuming arm movement towards the end of disk)

[9 Marks]

3

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QUESTION 3 [20 Marks]

P3

00

P4

P1

Re 3 Reso rce 4

P2

Figure 1

a) Consider the directed resource graph shown in Figure 1, and answer the following questions.

L

Identify all of the deadlocked processes.

ii. Can the deadlock be resolved without selecting a victim?

iii. Which requests by the three processes for resources from R2 would you satisfy to

minimize the number of processes involved in the deadlock?

iv. Conversely, which requests by the three processes for resources from R2 would

you satisfy to maximize the number of processes involved in deadlock?

[8 Marks]

b) Imagine that you are an unauthorized user who wants to break into your system. Describe how you might begin guessing the password of a legitimate user.

[3 Marks]

El

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c) Given the following information in Table 2 for a BATCH systems:

Table 2

Job Arrival Time CPU cycle A 0 12 B 0 14 C 0 6 D 2 3 E 3 16

i. Suggest TWO (2) processing scheduling algorithm that suits the system.

[2 Marks]

ii. Based on your answer in (i), calculate and recommend which is the best algorithm in terms of shortest average waiting and turnaround time.

[7 Marks]

QUESTION 4 [20 Marks] a) Network management has played an important role in the development of Network Operating

Systems (NOS) and Distributed Operating Systems (DOS). Based on these two variant of OS, answer the following questions.

i. Compare the advantages of an NOS with a DOS and explain which you would prefer to operate and why.

[4 Marks]

ii. If your DOS had four nodes, how many operating systems would it have? Explain your answer.

[2 Marks]

5

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iii. If your NOS had four nodes, how many operating systems would it have? Explain your reasons for your answer

[2 Marks]

b) Describe how primary storage differs from secondary storage.

[2 Marks] c) Take a look at user "FSKKP" home directory below and answer the following questions

-rwx------2 fskkp ump 2048 Jan 2 1013 quizdrwx------2 fskkp ump 2048 Jan 2 1013 midterm

i. What is the difference between the two files in the directory? [2 Marks]

ii. Based on the file permission on "midterm", what type of access can users from group "ump" have?

[2 Marks]

iii. A new user, Thomas was trying to view the content of "quiz" file but was denied. Investigate the problem and provide a solution so that he can view the content of the file.

[4 Marks]

iv. To modify the content of midterm directory, Abu tried to edit via VI editor but was denied. Investigate what is the problem.

[2 Marks] END OF QUESTION PAPER

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