A system transfer data blocks of 2000 bytes with programmed I/O, each byte…
2026
A system transfer data blocks of 2000 bytes with programmed I/O, each byte transfer takes 6 CPU cycles, with direct memory access (DMA), the block transfer takes 3000 Cycles total, with CPU setup overhead of 200 cycles. The CPU clock is 1 GHZ.
How much CPU time is consumed by DMA overhead?
- A.
0.2 μs
- B.
2.0 μs
- C.
3.0 μs
- D.
12.0 μs
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Correct answer: A
The DMA overhead is given as 200 CPU cycles. With a 1 GHz clock, each cycle takes 1 nanosecond (ns). Therefore, the CPU time consumed by DMA overhead is 200 ns. Converting to microseconds: 200 ns = 0.2 μs.