Operating System November 2017 Knec Past Paper

Outline three functions of the job control language ina computer system. (3 marks)
Explain each of the following terms as used in operating systems:
@ _ spooling;
(ii) warm boot;
(iii) context switch. (6 marks)
A disk has the following head movement queue 95, 190, 40, 115, 18, 123, 52, 60 with the read-write head initially at track 40 and the tail track at 210. With the aid of a Gantt graph, determine the total seek time using each of the following disk scheduling algorithms:
G) — shortest seek time first;
(ii) elevator assuming the head moves towards 0. (7 marks)
Explain two reasons why application programs are temporarily stored in the main memory of a computer system. (4 marks)
Outline three examples of systems calls for each of the following:
(i) file manipulation;
(ii) communication. (6 marks)
Explain two modes of processing supported by multiprocessing operating system. (4 marks)
Several programs can be run simultaneously using a multiprogramming operating system.
(i) Explain the objective of this mode of processing. (2 marks)
(ii) Explain the problem associated with this mode of processing. (2 marks)
Joseph intends to acquire an operating system for his company’s network system. Explain three factors he should consider other than cost. (6 marks)
The operating system uses various approaches of interfacing with users. Describe three such approaches. (6 marks)
Explain each of the modes of programmable clocks as used in I/O device management:
G) one-shot;
Gi) square-wave. (4 marks)
Distinguish between the CPU bound and I/O bound jobs during inter process communication. (4 marks)
Files can be stored on a directory using various logical structures. Describe three such structures that the operating system supports. (6 marks)
Outline three objectives of I/O scheduling in a computer system. (3 marks)
A system disk has been diagnosed to be having low access speed. Explain three ways in which the operating system could improve the performance of such a disk. (6 marks)
Outline two examples for each of the following types of interrupts within a computer system:
(i) external;
(ii) internal. (4 marks)
With the aid of a diagram, describe three of the layered structures of a file system as used in operating systems. (8 marks)
Differentiate between deadlock avoidance and deadlock prevention as used in operating systems. (4 marks)
Explain two circumstances under which a preemptive scheduling decision would be made by the operating system during inter-process communication. (4 marks)
Explain two disadvantages associated with linked file allocation method. (4 marks)
Distinguish between page and frame as used in memory management. (4 marks)
A deadlock can be eliminated by either of the following methods:
(ij) aborting deadlocked processes all at once;
(ii) aborting one process at a time until the deadlock is eliminated.
Describe a disadvantage associated with each elimination method. (4 marks)
Distinguish between each of the following process states as used in process control:
(i) running state and ready state;
(ii) blocked state and terminated state. (8 marks)

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