DIT30I  DBIT403  OPERATING SYSTEMS.

UNIVERSITY EXAMINATIONS: 2014/2015
EXAMINATION FOR THE DIPLOMA IN INFORMATION
TECHNOLOGY
DIT30I DBIT403 OPERATING SYSTEMS
DATE: AUGUST 2016 TIME: 1½HOURS
INSTRUCTIONS: Answer Any THREE Questions.

QUESTION ONE
(a) Citing suitable examples in case, describe three categories of Input/ Output (I/O) devices
(6 Marks)
(b)Differentiate between the following terms:-
(i) Single-partition allocation and multiple partition allocation method (4 Marks)
(ii) Buffering and caching (4 Marks)
(c) List and briefly explain three causes of computer interrupt (6 Marks)
QUESTION TWO
(a) Highlight three advantages of multi-user operating system (3 Marks)
(b)Giving an example in case, distinguish between the following terms:-
(i) System software and Application software (4 Marks)
(ii) Open Source software and Proprietary software (4 Marks)
(iii)Utility software and operating software (4 Marks)
(c) Highlight three access permissions that can be assigned to a file through the support of an
operating system (3 Marks)
(d) Outline two types of user interfaces supported by computer operating systems (2 Marks)
QUESTION THREE
(a) Giving an example in case, state three criteria of classifying operating systems (6 Marks)
(b) List four file extensions supported by window based operating systems (3 Marks)
(c) An organization intends to purchase a new operating system to be used in the Personal
computers in the organization.
Required:
Justify five factors the company management should put into consideration while buying the
required operating systems (5 Marks)
(d) The operating system act as the resource manger of a computer system. Highlight six
functions which are performed by an operating system in managing a computer’s resources
(6 Marks)
QUESTION FOUR
(a) A file system supports a collection of operations that can be performed on directories.
Describe three such operations (6 Marks)
(b) Njoroge intends to design an operating system to use the following schemes to prevent
deadlocks:
(i) Preemption
(ii) Resource ordering
Required: Explain the above schemes and give one advantage and one disadvantage of each
scheme (6 Marks)
(c) Outline three differences between FAT filing system and NTFS (6 Marks)
(d) Explain the term ‘processing scheduling’ as used in operating systems (2 Marks)
QUESTION FIVE
(a) With the aid of a diagram, outline the five state process model as used in operating systems
(5 Marks)
(b) Figure 1 shows typical information of process control block (PCB).
Identifier
State
Priority
Program Counter
Memory Pointers
Figure 1
Required: state the function of each PCB element: – (5 Marks)
(c) Briefly describe the following process scheduling algorithms:-
(i) FIFO (3 Marks)
(ii) Priority scheduling (3 Marks)
(d) Explain the functions of the following process schedulers:-
(i) Short term scheduler (2 Marks)
(ii) Medium term scheduler (2 Marks)

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