Consider a single - level page table system, with the page table stored in the memory. If the hit rate to TLB is 80%, and it takes 15 nano seconds to search the TLB, and 150 nano seconds to access the main memory, then what is the effective memory access time, in nano seconds?                             NTA NET JUNE 2020 

Consider a hypothetical machine with 3 pages of physical memory, 5 pages of virtual memory, and <A,B,C,D,A,B,E,A,B,C,D,E,B,A,B> as the stream of page references by an application. If P and Q are the number of page faults that the application would incur with FIFO and LRU page replacement algorithms respectively, (P,Q) = ________. (Assuming enough space for storing 3 page frames).                                 NTA NET JUNE 2020 

Consider a disk system having 60 cylinders. Disk requests are received by a disk drive for cylinders 10,22,20,2,40,6 and 38, in that order. Assuming the disk head is currently at cylinder 20, what is the time taken to satisfy all the requests if it takes 2 milliseconds to move from one cylinder to adjacent one and Shortest Seek Time First(SSTF) algorithm is used?                         NTA NET JUNE 2020 

Identify the circumstances under which pre-emptive CPU scheduling is used:                 NTA NET DECEMBER 2019 
A. A process switches from Running state to Ready state
B. A process switches from Waiting state to Ready state
C. A process complete its execution
D. A process switches from Ready to Waiting state
Choose the correct option:

Which of the following inter-process communication model is used to exchange messages among co-operative processes?                NTA NET DECEMBER 2019 

Suppose a system has 12 magnetic tape drives and at time T, three processes are allotted tape drives out of their need as given below:                  NTA NET DECEMBER 2019 

Process	Maximum Needs	Current Needs
P0	10	5
P1	4	2
P2	9	2

At time T, the system is in safe state. Which of the following is safe sequence so that deadlock is avoided?

Which of the following CPU scheduling algorithms is/are supported by LINUX operating system? NTA NET DECEMBER 2019 

Consider a paging system where translation look aside buffer (TLB) a special type of associative memory is used with hit ratio of 80%. Assume that memory reference takes 80 nanoseconds and reference time to TLB is 20 nanoseconds. what will be the effective memory access time given 80% hit ratio?       NTA NET DECEMBER 2019 

A counting semaphore is initialized to 8. 3 wait() operation and 4 signal() operations are applied. Find the current value of semaphore variable.                          NTA NET DECEMBER 2019 

Given CPU time slice of 2ms and following list of processes.

Process	Burst Time	Arrival Time
P1	3	0
P2	4	2
P3	5	5

Find the average turnaround time and average waiting time using round robin CPU Scheduling?                     NTA NET DECEMBER 2019 

At a particular time of computation, the value of counting semaphore is 10. Then 12 P Operations and "x" V operations were performed on this semaphore. If the final value of semaphore is 7, x will be:                           CBSE NET JULY 2018 

In a paged memory, the page hit rate is 0.40. The time required to access a page in secondary memory is equal to 120ns. The time required to access a page in primary memory is 15ns. The average time required to access a page is ________                               CBSE NET JULY 2018 

Normally user programs are prevented from handling I / P directly by I / O instructions in them. For CPUs having explicit I / O instructions, such I / O protection is ensured by having the I / O instructions privileged. In a CPU with memory mapped I / O, there is no explicit I / O instruction. Which one of the following is true for a CPU with memory mapped I / O?                                                    CBSE NET JULY 2018 

Which UNIX / Linux command is used to make all files and sub - directories in the dictionary "progs" executable by all users?                                        CBSE NET JULY 2018 

Which of the following statements are true?                                CBSE NET JULY 2018 

A. External fragmentation exists when there is enough total memory space to satisfy a request but the available space is contiguous.

B. Memory fragmentation can be internal as well as external.

C. One solution to external fragmentation is compaction.

Page information in memory is also called as Page table. The essential contents in each entry of a page table is / are ______.

Consider a virtual page reference string 1, 2, 3, 2, 4, 2, 5, 2, 3, 4. Suppose LRU page replacement algorithm is implemented with 3 page frames in main memory. Then the number of page faults are _________.                                               CBSE NET JULY 2018 

Consider the following three processes with the arrival time and CPU burst time given in milliseconds:                             CBSE NET JULY 2018 

Process	Arrival Time	Burst Time
P1	0	7
P2	1	4
P3	2	8

The average waiting time for preemptive SJF Scheduling algorithm is _______ .

In which of the following scheduling criteria, context switching will never take place?                                        CBSE NET JULY 2018 

In Linux operating system environment ______ command is used to print a file.                                          CBSE NET JULY 2018 

To overcome difficulties in Readers - Writers problem, Which of the following statements is / are true?                                  CBSE NET JULY 2018 

(i) Writers are given exclusive access to shared objects.

(ii) Readers are given exclusive access to shared objects.

(iii) Both Readers and Writers are given exclusive access to shared objects.

Choose the correct answer from the code given below:

Suppose a system has 12 instances of some resources with n processes competing for that resource. Each process may require 4 instances of the resource. The maximum value of n for which the system never enters into deadlock is                              CBSE NET JULY 2018 

Dirty bit is used to show the                                                                     CBSE NET JULY 2018 

Suppose for a process P, reference to pages in order are 1,2,4,5,2,1,2,4. Assume that main memory can accommodate 3 pages and the main memory has already pages 1 and 2 in the order 1 - first, 2 - second. At this moment, assume FIFO Page Replacement Algorithm is used then the number of page faults that occur to complete the execution of process P is                                 CBSE NET JULY 2018 

Consider the following set of processes and the length of CPU burst time given in milliseconds:                                             CBSE NET JULY 2018 

Process	CPU Burst Time (ms)
P1	5
P2	7
P3	6
P4	4

Assume that processes being scheduled with Round-Robin Scheduling Algorithm with time quantum 4 ms. Then the waiting time for P₄ is _____ ms

Suppose P,Q and R are co-operating processes satisfying Mutual Exclusion condition. Then, if the process Q is executing in its critical section then                              CBSE NET JULY 2018 

A process residing in Main Memory and Ready and Waiting for execution, is kept on                                   CBSE NET JULY 2018 

___________ system call creates new process in Unix.                                                      CBSE NET JULY 2018