1. Consider a computer with 8 Mbytes of main memory and a 128 K cache. The cache block size is 4 K. It uses a direct mapping scheme for cache management. How many different main memory blocks can map onto a given physical cache block ?

2048

256

64

None of these

2. The first-fit, best-fit and the worst-fit algorithm can be used for

contiguous allocation of memory

linked allocation of memory

indexed allocation of memory

all of these

3. If there are 32 segments, each of size 1 K byte, then the logical address should have

13 bits

14 bits

15 bits

16 bit

4. Dirty bit is used to show the

page with corrupted data

the wrong page in the memory

page that is modified after being loaded into cache memory

page that is less frequently accessed

5. In real-time operating systems, which of the following is the most suitable scheduling scheme?

round-robin

first-come-first-served

preemptive

random scheduling

6. 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

7. 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

8. Distributed systems should

meet prescribed time constraints

aim better resource sharing

aim better system utilization

aim low system overhead

9. Fence register is used for

CPU protection

memory protection

file protection

all of these

10. 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