A hard disk with a transfer rate of 10 Mbyte/s is constantly

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A hard disk with a transfer rate of 10 Mbyte/s is constantly transferring data to memory using DMA. The processor runs at 600 MHz, and takes 300 and 900 clock to initiate and complete DMA transfer respectively. If the size of the transfer is 20 kbyte, what is the percentage of processor time consumed for the transfer operation?

1. 5.0%
2. 1.0%
3. 0.5%
4. 0.1%

Correct Option: D

Transfer rate = 10 MB ps
Data = 20 KB
Transfer rate =10 Mb ps
DATA = 20 kb
Time = (20 × 2¹⁰)/10 × 2²⁰ = 2 × 10³ = 2 ms
Processor speed = 600 MHz = 600 cycles/ sec
Cycles required by CPU = 300 + 900, For DMA =1200
Time =1200 / (600 × 10⁶) = 0.002 ms