11. The maximum amount of information that is available in one portion of the disk access arm for a removal disk pack (without further movement of the arm with multiple heads) [Paper II December 2011]
(A) a plate of data
(B) a cylinder of data
(C) a track of data
(D) a block of data
12. Which of the following is scheme to deal with deadlock? [Paper III June 2012]
(A) Time out
(B) Time in
(C) Both (A) & (B)
(D) None of the above
13. A computer system supports 32 bit virtual address as well as 32 bit physical addresses. Since the virtual address space is of same size as that of physical address space, if we want to get rid of virtual memory, which one of the following is true? [Paper III June 2012]
(A) Efficient implementation of multi-user support is no longer possible.
(B) The processor cache can be made more efficient.
(C) Hardware support for memory management is not needed.
(D) CPU scheduling can be made more efficient.
14. A user level process in Unix traps the signal sent on a Ctrl + C input and has a signal handling routine that saves appropriate files before terminating the process. When a Ctrl + C input is given to this process, what is the mode in which the signal handling routine executes? [Paper III June 2012]
(A) User mode
(B) Kernel mode
(C) Superuser mode
(D) Privileged mode
15. Consider the methods used by processes P1 and P2 for accessing their critical sections. The initial values of shared Boolean variables S1 and S2 are randomly assigned,
Which one of the following statements describes the properties achieved? [Paper III June 2012]
P1 P2
while (S1 = = S2); while (S1 = = S2);
critical section critical
section
S1 = S2; S1
= S2;Which one of the following statements describes the properties achieved? [Paper III June 2012]
(A) Mutual exclusion but not progress
(B) Progress but not mutual exclusion
(C) Neither mutual exclusion nor progress
(D) Both mutual exclusion and progress
16. What is the meaning of ‘Hibernate’ in Windows XP/Windows 7? [Paper III June 2012]
(A) Restart the computers in safe mode.
(B) Restart the computers in normal mode.
(C) Shutdown the computer terminating all the running applications.
(D) Shutdown the computer without closing the running applications.
17. Which one of the following options is not a shell in UNIX system? [Paper III June 2012]
(A) Bourne Shell
(B) C Shell
(C) Net Shell
(D) Korn Shell
18. What deletes the entire file except the file structure? [Paper II June
2012]
(A) ERASE (B) DELETE
(C) ZAP (D) PACK
19.
Which command is the fastest among the following? [Paper II June
2012]
(A) COPY TO
<NEW FILE>
(B) COPY
STRUCTURE TO <NEW FILE>
(C) COPY FILE
<FILE 1> <FILE 2>
(D) COPY TO
MFILE-DAT DELIMITED
20.
In round robin CPU scheduling as time quantum is increased the
average turn-around-time [Paper
II June 2012]
(A) increases
(B) decreases
(C) remains
constant
(D) varies
irregularly
SOLUTIONS
11. B
Data is read from disk by positioning the arm on the correct track and then rotating the disk to read data in the track. Same tracks in different plates form a cylinder. So data can be read from a cylinder without further moving the arm provided it has multiple heads for reading.
 |
| Disk showing track and cylinder |
12. A
One of the for necessary conditions required for deadlock to occur is hold-and-wait. This can be avoided by adding time-out for the resource or the process. That is a process waiting for more than a fixed amount of time should stop waiting and release all the resources acquired by that. Or any resource that is held by a process for more than a fixed amount of time should be released.
13. A
14. ?
15. C
As both S1 and S2 are assigned random values initially, both can be same, in which case both processes wait indefinitely without entering critical section. Even if S1 != S2 initially, when one process executes the critical section and exits S1 is equated to S2, Neither process P1 or P2 can enter critical section after this. So there is no progress.
Now considering mutual exclusion, when S1 !=S2, suppose P1 enters critical section and is executing it, at the same time P2 checks for the values of S1 and S2, finds they are same and enters the critical section. So there is no mutual exclusion also. This can be solved by modifying the code as
As both S1 and S2 are assigned random values initially, both can be same, in which case both processes wait indefinitely without entering critical section. Even if S1 != S2 initially, when one process executes the critical section and exits S1 is equated to S2, Neither process P1 or P2 can enter critical section after this. So there is no progress.
Now considering mutual exclusion, when S1 !=S2, suppose P1 enters critical section and is executing it, at the same time P2 checks for the values of S1 and S2, finds they are same and enters the critical section. So there is no mutual exclusion also. This can be solved by modifying the code as
P1 P2
while (S1 = = S2); while (S1 = = S2);
S1 = S2; S1 = S2 = true;
critical section critical section
S1 = !S2; S1 = !S2;
Here both processes P1 and P2 sets S1=S2 before entering the critical section, so no other process can enter. So Mutual exclusion is attained, Also once the execution of critical section is over, the process makes S1!=S2, so that any waiting process can enter.
16. D
17. C
PACK: Shrinks file into one small (compressed) file so that it does not take as much space up.
ZAP: Removes all records from a table, leaving just the table structure.
ERASE/DELETE is a command used to remove files from your computer's hard drive or other writeable media.
19. ?
20. B
The round-robin scheduling algorithm is designed especially for time-sharing systems. It is similar to FCFS scheduling, but pre-emption is added to switch between processes. A small unit of time, called a time quantum or time slice, is defined. When a process finishes the time quantum it is switched and the next process in queue is taken for execution.
Turnaround Time is the time elapsed from when process is submitted to when it is completed. It includes execution time and waiting time and switching time between processes.
When the time quantum is increased, the no. of times the process is switched decreases reducing the switching time between processes. So Average turn around time gets reduced
The shell provides you with an interface to the UNIX system. It gathers input from you and executes programs based on that input. When a program finishes executing, it displays that program's output.A shell is an environment in which we can run our commands, programs, and shell scripts.
In UNIX there are two major types of shells:
- The Bourne shell. If you are using a Bourne-type shell, the default prompt is the $ character.
- The C shell. If you are using a C-type shell, the default prompt is the % character.
- Bourne shell (sh)
- Korn shell (ksh)
- Bourne Again shell (bash)
- POSIX shell (sh)
- C shell (csh)
- TENEX/TOPS C shell (tcsh)
PACK: Shrinks file into one small (compressed) file so that it does not take as much space up.
ZAP: Removes all records from a table, leaving just the table structure.
ERASE/DELETE is a command used to remove files from your computer's hard drive or other writeable media.
19. ?
20. B
The round-robin scheduling algorithm is designed especially for time-sharing systems. It is similar to FCFS scheduling, but pre-emption is added to switch between processes. A small unit of time, called a time quantum or time slice, is defined. When a process finishes the time quantum it is switched and the next process in queue is taken for execution.
Turnaround Time is the time elapsed from when process is submitted to when it is completed. It includes execution time and waiting time and switching time between processes.
When the time quantum is increased, the no. of times the process is switched decreases reducing the switching time between processes. So Average turn around time gets reduced
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