1. In a paged memory, the page hit ratio is 0.35. The time required to access a page in secondary memory is equal to 100 ns. The time required to access a page in primary memory is 10 ns. The average time required to access a page is

3.0 ns

68.0 ns

68.5 ns

78.5 ns

2. Working set (t, k) at an instant of time, t, is

the set of k future references that the operating system will make

the set of future references that the operating system will make in the next 'k' time units

the set of k reference with high frequency

the set of pages that have been referenced in the last k time units

3. Distributed systems should

meet prescribed time constraints

aim better resource sharing

aim better system utilization

aim low system overhead

4. Fence register is used for

CPU protection

memory protection

file protection

all of these

5. Determine the number of page faults when references to pages occur in the following order : 1, 2, 4, 5, 2, 1, 2, 4. Assume that the main memory can accommodate 3 pages and the main memory already has the pages 1 and 2, with page 1 having been brought earlier than page 2. (LRU algorithm is used)

3

5

4

None of these

6. A certain moving arm disk storage with one head has following specifications : Number of tracks I recording surface 100 Disk rotation speed 2400 rpm Track storage capacity= 62500 bits The transfer rate will be

2.5 Mbits/s

4.25 Mbits/s

1.5Mbits/s

3.75Mbits/s

7. A certain moving arm disk storage with one head has following specifications : Number of tracks I recording surface 100 Disk rotation speed 2400 rpm Track storage capacity= 62500 bits The average latency time (assume the head can move from one track to another only by traversing the entire track) is

2.5 s

2.9 s

3.1 s

3.6 s

8. Poor response time are caused by

Process or busy

High I/O rate

High paging rates

All of these

9. Disk sheduling involves deciding

which disk should be accessed next

the order in which disk access requests must be serviced

the physical location where files should be accessed in the disk

none of these

10. Disk requests come to a disk driver for cylinders 10, 22, 20, 2, 40, 6 and 38, in that order at a time when the disk drive is reading from cylinder 20. The seek time is 6 ms per cylinder. If the scheduling algorithm is the closest cylinder next, then the total seek time will be

360 ms

876 ms

850 ms

900 ms