OS Input Output Systems

Question 61

Consider a disk pack with 16 surfaces, 128 tracks per surface and 256 sectors per track. 512 bytes of data are stores in a bit serial manner in a sector. The capacity of the disk pack and the number of bits required to specify a particular sector in the disk are respectively

• 256 Mbyte, 19 bits
• 256 Mbyte, 28 bit
• 512 Mbyte, 20 bits
• 64 Gbyte, 28 bits

Question 62

Special software to create a job queue is called a

• Driver
• Spooler
• Interpreter
• Linkage editor

Question 63

The total time to prepare a disk drive mechanism for a block of data to be read from it is

• seek time
• latency
• latency plus seek time
• transmission time

Question 64

Feedback queues

• are very simple to implement
• dispatch tasks according to execution characteristics
• are used to favour real time tasks
• require manual intervention to implement properly

Question 65

Which of the following is an example of spooled device?

• A line printer used to print the output of a number of jobs
• A terminal used to enter input data to a running program
• A secondary storage device in a virtual memory system
• A graphic display device

Question 66

A read bit can be read

• and written by CPU
• and written by peripheral
• by peripheral and written by CPU
• by CPU and written by the peripheral

Question 67

Disk requests are received by a disk drive for cylinder 5, 25, 18, 3, 39, 8 and 35 in that order. A seek takes 5 msec per cylinder moved. How much seek time is needed to serve these requests for a Shortest Seek First (SSF) algorithm? Assume that the arm is at cylinder 20 when the last of these requests is made with none of the requests yet served

• 125 msec

• 295 msec

• 575 msec

• 750 msec

Question 68

Match the following components of an expert system :

List - I	List - II
(a) I/O interface	(i) Accepts user’s queries and responds to question through I/O interface
(b) Explanation module	(ii) Contains facts and rules about the domain
(c)Inference engine	(iii)Gives the user, the ability to follow inferencing steps at any time during consultation
(d)Knowledge base	(iv)Permits the user to communicate with the system in a natural way

codes:

	(a)	(b)	(c)	(d)
(A)	(i)	(iii)	(iv)	(ii)
(B)	(iv)	(iii)	(i)	(ii)
(C)	(i)	(iii)	(ii)	(iv)
(D)	(iv)	(i)	(iii)	(ii)

• (A)
• (B)
• (C)
• (D)

Question 69

A particular disk unit uses a bit string to record the occupancy or vacancy of its tracks, with 0 denoting vacant and 1 for occupied. A 32-bit segment of this string has hexadecimal value D4FE2003. The percentage of occupied tracks for the corresponding part of the disk, to the nearest percentage is

• 12
• 25
• 38
• 44

Question 70

A computer has 1000 K of main memory. The jobs arrive and finish in the sequence Job 1 requiring 200 K arrives Job 2 requiring 350 K arrives Job 3 requiring 300 K arrives Job 1 finishes Job 4 requiring 120 K arrives Job 5 requiring 150 K arrives Job 6 requiring 80 K arrives Among best fit and first fit, which performs better for this sequence?

• First fit
• Best fit
• Both perform the same
• None of the above