# Find the average access time for the disk. 4m Dec2007

By | July 8, 2015

Seek time on a hard disk is 50 ms. it rotates at a speed of 3000 rotations/sec. Each track on the disk has 100 sectors. Find the average access time for the disk. 4m Dec2007

Disk Rotation Speed = 3000 rps.  (i.e. 180000 rpm)

Sectors per Track = 100 sectors

Seek time = 50 millisecond

Convertion is Shown Below:

Rotational latency = Average seek time + Average Rotational delay + Controller Overheads

Average seek time = 50 millisecond (given)

Calculate

Average Rotational delay = ½ Time of Rotation in milliseconds

Average Rotational delay = ½ * (60/180000) *1000 millisecond

= ½ * 1/3 millisecond

= 1/6 millisecond

= 0.166 millisecond

Note:-  Controller Overheads (optional) not using it For Now.

Rotational latency = Average seek time + Average Rotational delay

Rotational latency = 50 millisecond + 0.166 millisecond

= 50 + 0.166 millisecond

= 50.166 millisecond.

(d) Explain, with an example of each call, any five DOS function calls supported by INT 21H in the 8086 assembly language.             10

(e) Explain, with an example, the following logic-microoperations:                       6

1.      Selective complement
3.      Insert
4.      Clear

(f) What is the need of master slave flip-flop? Explain its functioning with the help of a suitable diagram.  6

Refer :- MCS-012 Block 1 page 93 and 94

(g) Write a program to evaluate the following expression using an accumulator machine: 7

A = B + C * D * E + F