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A 10,000 rpm (revolutions per minute) harddisk can transfer data at a rate of 16

ID: 3552260 • Letter: A

Question

A 10,000 rpm (revolutions per minute) harddisk can transfer data at a rate of 160 Mbps (megabits

per second). The time to find a track is negligible. Determine the data amount for which it takes

as long to transfer it off the disk as the time it takes to find the right sector.

- Step 1: Determine the time it takes for a half-rotation. Hint: compute the number of

revolutions per millisecond and work from there.

- Step 2: Translate the data transfer into kilobytes per millisecond.

- Step 3: Multiply the two numbers together to get the data amount.

Explanation / Answer

Number of revolution in a minute (= 60000 milliseconds) = 10000

Number of revolutionin 1 millisecond = 1 / 6

So for a half revoltion the time required = 3 milliseconds


Data Transfer = 160 X 1024 Kb/1000 s = 163.84 Kb/milliseconds


Data amount = 163.84 X 3 = 491.52 Kb