Suppose a given bus protocol requires 4 ns for devices to make requests, 8 ns fo
ID: 3737126 • Letter: S
Question
Suppose a given bus protocol requires 4 ns for devices to make requests, 8 ns for arbitration, and 15 ns to complete each operation. How many operations are completed per second? a. A hard disk with 4 platters has 1024 tracks/platter, 1024 sectors/track, and 512 bytes/sector. If the platter rotation speed is 15,000 rpm with 1 ms seek time for every 100 tracks traversed. Calculate the following:i. Total capacity of this hard disk (3 marks)ii. The average seek time (4 marks)iii. The average rotational latency (3 marks)iv. The transfer time for a sector (3 marks)v. The average access time (3 marks)Explanation / Answer
Request time use only ones because after request approved ,there is no need to requst
and arbitration time like a acknowledgement time, used for acknowledge the sender
one second = 1000 ns
time for operation = 1000-4 = 996
Operation per second= 996 / 23 = 43.30 = 43
2-------------------------
i
total capacity of disk = 4*1024*1024*512
= 22*210*210*29
= 231
= 2 GB
ii)----no of track per platter = 1024
1 ns seek time for 100 track
average seek time = 1024/100 * 1ms
= 10.24ms
iii)--- 15000 rotation = 60 second
1 rotation = 60/ 15000 = 1/250
Average rotational latency = 1/250 * 1/2
= 2 ms
iv)--- 1 track rotate = 2/1024 ms
1 sector rotate = 2/ 1024*1024
=1.9 * 10-6
v)------
Average access time = seek time + rotational time + transfer rate
= 10.24 ms + 2ms + 1.9*10-6
= 12.24 ms
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