895 views
0 votes
0 votes
A DMA module is transferring bytes to memory using cycle stealing mode from a device transmitting at 16 KB/s. The processor is fetching instructions at the rate of 1 MB/s. The percentage by which the processor will be slowed down due to the DMA activity is ______

1 Answer

Best answer
1 votes
1 votes

A DMA module is transferring bytes to memory using cycle stealing mode

Since number of bytes is not clear. Lets assume you mean to say we are transferring 1 byte of data to memory using cycle stealing mode.
Device transfer speed = 16 KB/s
Processor speed = 1 MB/s

Preparation time ( x ) 
16 KB = 1 sec
1 B  = $\frac{1}{16 \times 10^{3}}$ sec = 62.5 $\mu$ sec

Transfer time ( y )
1MB = 1 sec
1B = $\frac{1}{10^{6}}$  =  1 $\mu$ sec

In cycle stealing mode, % of time cpu is busy  = $\frac{1}{ 62.5} \times 100$ = 1.6 %

Read more about it here : https://gateoverflow.in/140573/%25-time-of-cpu-blocked-in-dma

selected by

No related questions found