UNIVERSITY EXAMINATIONS: 2010/2011
FIRST YEAR EXAMINATION FOR THE DEGREE OF BACHELOR OF
SCIENCE IN INFORMATION TECHNOLOGY
BIT 1302: OPERATING SYSTEMS
DATE: AUGUST 2011 TIME: 2 HOURS
INSTRUCTIONS: Answer question ONE and any other TWO questions
Question One
a) Distinguish between the following pairs of terms:
i) Deadlock and Starvation [2 Marks]
ii) Kernel mode and User mode [2 Marks]
iii) Network and Distributed operating systems [2 Marks]
iv) Time sharing and Real time operating systems [2 Marks]
b) Outline four services provided by the operating system. [4 Marks]
c) With the aid of process transition diagrams discuss the following process state.
i. Two state process model [3 Marks]
ii. Three state process model [3 Marks]
iii. Five state process model [3 Marks]
d) With the aid of diagrams describe each of the following approaches of structuring operating
systems,
i. The layered approach [3 Marks]
ii. Monolithic approach [3 Marks]
iii. Client server approach [3 Marks]
Question Two
a) i. Define mutual exclusion [2 Marks]
ii. Discuss the mechanisms for achieving mutual exclusion. [6 Marks]
b) Most Modern Operating Systems support memory management with paging. Explain the
following.
i) Page fault [2 Marks]
ii) Replacement algorithms for paged system [6 Marks]
c) State four benefits of virtual memory [4 Marks]
Question Three
a) Discuss the objectives of I/O management. [4 Marks]
b) Identify four principles of input, output software. [4 Marks]
c) Distinguish between file protection and security. [2 Marks]
d) The manifestation of a process within the operating system is achieved by the Process Control
Block (PCB).
i) Explain the kinds of information maintained by the PCB [6 Marks]
ii) Explain the role the PCB plays during interrupt handling [4 Marks]
Question Four
a) Give a brief description of blocking, non-blocking and asynchronous I/O. [6 Marks]
b) Explain two approaches that can be used to store files in a disk pointing out advantages and
disadvantages of each. [6 Marks]
c) Describe the information, which would be stored in a typical directory system pertaining to the file
within the directory [4 Marks]
d) Give four advantages of using directories. [4 Marks]
Question Five
a) Security goals of any computer system are decided by its security policies. Briefly explain three
computer security goals that can be set in an operating system. [6 Marks]
b) Identify five types of security threats to consider when designing and implementing any operating
system. [5 Marks]
i) Distinguish between a Preemptive and a non-preemptive scheduling [4 Marks]
ii) Name one preemptive scheduling algorithm and one non-preemptive scheduling
algorithm. [2 Marks]
c) Explain briefly the difference between authorization and authentication [3 Marks]
