OS Concepts

(1) When the result of computation depends on the speed of the processes involved there is said to be
A deadlock A time lock Cycle stealing Race condition

(2) Consider a counting semaphore which was initialized to 10 and then 6P (wait) operation and 4v (signal) operations were completed on this semaphore. What is the resulting value of semaphore?
10 9 8 0

(3) Software interrupt is required by the processor to
Return from subroutine Obtain system services, which need execution of privileged instruction Test the interrupt system of the processor Implement co-routines

(4) How many child processes are created if a process executes the code fork();fork();fork();
5 8 7 9

(5) If hardware does not support _________ a multi-user, multi-processing operating system cannot be implemented.
At least two modes of CPU execution Demand paging DMA for disk transfer Address translation

Operating system test questions for interview

(1) The use of __________ works on the principle of locality.
Cache memory Interrupts Polling DMA

(2) Consider a computer system with 6 tape drives and n processes completing for them. What is the maximum value of n for the system to be deadlock free assuming each processes may need 3 tape drives?
3 2 4 7

(3) When size of the memory is increased the page replacement policy that sometimes leads to more page faults is
FIFO Optimal LRU None of the above

(4) The capacity of a memory unit = The number of words x The number of bits/words. For the memory of 4k x 16 the number of separate address and data lines needed is
12 address and 16 data lines 12 address and 12 data lines 11 address and 6 data lines 12 address and 8 data lines

(5) A system has m number of resources of same type and 3 processes A, B and C. share these resources. A, B and C have the peak demand of 3, 4 and 6 respectively. Deadlock will not occur if
m = 15 m = 8 m = 13 m = 9