Ics2202:Operating Systems I Question Paper
Ics2202:Operating Systems I
Course:Bachelor Of Information Technology
Institution: Meru University Of Science And Technology question papers
Exam Year:2010
QUESTION ONE – (30 MARKS)
(a) Identify six objectives of a good scheduling algorithm assuming that the operating system is aimed primarily at interactive operations. (6 Marks) (b) Identify six ways of minimizing threats to systems. (6 Marks) (c) When a page fault occurs, the operating system has to choose which page to remove from the memory to make room for the page that has to be brought in. Describe any three page replacement algorithms. (6 Marks) (d) Describe the elements for the process control table/block (6 Marks) (e) Briefly describe the following terms: (i) Deadlock (ii) Virtual memory (iii) Swapping (6 Marks)
QUESTION TWO – (20 MARKS)
(a) Memory management is one of the most important services provided by the operating system. Give four major responsibilities of the operating system in managing memory. (4 Marks) (b) Briefly define multitasking, multiprogramming and multiprocessing. (6 Marks) (c) Explain the four conditions needed to hold to have a good solution for the critical section problem (mutual exclusion). (4 Marks)
(d) Consider a swapping system in which memory consists of the following hole sizes in memory order: 10KB, 4 KB, 20 KB, 18 KB, 7 KB, 9 KB, 12 KB and 15 KB. Which hole is taken for successive segment requests of (i) 12 KB (ii) 10 KB (iii) 9 KB
For first fit, best fit, worst fit and next fit (6 Marks)
QUESTION THREE – (20 MARKS)
(a) The concept of process is central to multitasking operating systems. Draw and discuss the various process states, and articulate the various state transitions along with a brief explanation of typical circumstances that would cause a process to make each of the transitions. (8 Marks) (b) One approach in deadlock recovery is process termination. Explain? (2 Marks) (c) Describe the algorithms for memory allocation, when using dynamic memory allocation with linked lists. (4 Marks) (d) List six file operations typically provided by an operating system giving the use of each operation. (6 Marks)
QUESTIO FOUR – (20 MARKS)
(a) CPU Scheduling deals with the problem of deciding which of the processes in the ready queue is to be allocated the CPU. Briefly describe clearly any three scheduling algorithms that are pre-emptive. (6 Marks) (b) Distinguish between deadlock prevention and deadlock avoidance. (4 Marks) (c) Mention and describe two ways of accessing files. (4 Marks) (d) A computer has four page frames. The time of loading, time of access, and R and M bits for each page are as shown below (the times are in clock ticks): Page Loaded Last ref. R M
0 126 280 1 0
1 230 265 0 1
2 140 270 0 0
3 110 285 1 1
(i) Which page will NRU replace? (ii) Which page will FIFO replace? (iii) Which page will LRU replace?
(iv) Which page will second chance replace? (6 Marks)
QUESTION FIVE – (20 MARKS)
(a) Briefly describe the conditions necessary for a deadlock situations hold. (6 Marks) (b) The speed of processors and main memory has far outstripped that of disk access. Outline any four disk Performance Parameters. (4 Marks) (c) Consider the following set of processes whose arrival times on the ready queue and the lengths of their CPU bursts given in milliseconds.
Process Arrival Time
Waiting Time (WT)
CPU burst (mseconds)
Turnaround Time(TT)
P1 0 6
P2 3 3
P3 6 12
Using the Quantum of THREE milliseconds, draw Gantt charts for FCFS, SJF, SRTN and RR Scheduling algorithms. (6 Marks)
(d) Files can be structured in several ways. Identify three most common possibilities. (4 Marks
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