A directory of Objective Type Questions covering all the Computer Science subjects. Here you can access and discuss Multiple choice questions and answers for various compitative exams and interviews.

11. Consider n processes sharing the CPU in round robin fashion. Assuming that each process switch takes s seconds. What must be the quantum size q such that the overhead resulting from process switching is minimized but, at the same time each process is guaranteed to get its turn at the CPU at least every t seconds ? 
a. q ≤ (t – ns)/ (n – 1)
b. q≥(t−ns)/(n−1)
c. q ≤ (t - ns)/ (n + 1)
d. q ≥ (t - ns)/(n + 1)
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Answer: (b).q≥(t−ns)/(n−1)

12. The virtual address generated by a CPU is 32 bits. The Translation Look-aside Buffer (TLB) can hold total 64 page table entries and  4-way set associative (i.e.with4-cache lines in the set). The page Sill' is 4 KB. The minimum size of TLB tag is
a. 12 bits
b. 15 bits
c. 16 bits
d. 20 bits
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Answer: (c).16 bits

13. Consider a disk queue with request for input/output to block on cylinders

98,183,37,122,14, 124, 65, 67 in that order

Assume that disk head is  initially positioned at cylinder 53  and moving towards cylinder number 0. The total number of head movements using Shortest Seek lime First (SSTF) and SCAN algorithms are respectively
a. 236 and 252 cylinders
b. 640 and 236 cylinders
c. 235 and 640 cylinder
d. 235 and 252 cylinders
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Answer: (a).236 and 252 cylinders

14. How much space will be required to store the bit map of a 1.3 GB disk with 512 bytes block size
a. 332.8 KB
b. 836 KB
c. 266.2 KB
d. 256.6 KB
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Answer: (a).332.8 KB

15. Translation Look-aside Buffer (TLB) is
a. a cache-memory in which item to be searched is compared on.e-by-one with the keys
b. a cache-memory in which item to be searched is compared with all the keys simultaneously
c. an associative memory in which item to be searched is compared one-by-one with the keys
d. an associative memory in which item to be searched is compared with all the keys simultaneously
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Answer: (d).an associative memory in which item to be searched is compared with all the keys simultaneously

16. Simplest way of deadlock recovery is
a. Roll Back
b. Preempt resource
c. Lock one of the processes
d. Kill one of the processes
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Answer: (a).Roll Back

17. Possible thread states in Windows 2000 operating system include
a. Ready, running and waiting
b. Ready, standby, Running,waiting, transition ,terminated
c. Ready, running, . waiting, transition and terminated
d. Standby,  running, transition and terminated
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Answer: (b).Ready, standby, Running,waiting, transition ,terminated

18. Which of the following conditions does not hold good for a solution to a critical section problem?
a. No assumptions may be made about speeds or the number of CPUs.
b. No two processes may be simultaneously inside their critical sections.
c. Processes running outside its critical section may block other processes.
d. Processes do not wait forever to enter its critical section.
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Answer: (a).No assumptions may be made about speeds or the number of CPUs.

19. In a demand paging memory system, page table is held in registers. The time taken to service a page fault is 8 m.sec. If an empty frame is available or if the replaced page is not modified, and it takes 20 m.sec., if the replaced page is modified. What is the average access time to service a page fault assuming that the page to be replaced is modified 70% of the time?
a. 11.6 m.sec
b. 16.4 m.sec
c. 28 m.sec
d. 14 m.sec
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Answer: (a).11.6 m.sec

20. The directory can be viewed as _______ that translates filenames into their directory entries.
a. Symbol table
b. Partition
c. Swap space
d. Cached
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Answer: (a).Symbol table

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