DMA Controller vs CPU

Question

I have a bit of a math problem here and it goes something like this:

CPU clock speed = 2MHz CPU performance = 2 MIPS.

Data Transmission speed of a scanner = 9600 bytes per second.

Direct Memory Access (DMA) controller transfers 16-bit data from scanner to memory in one clock cycle using cycle stealing.

If such a controller is attached with a system, then calculate the percentage of speed dropped by using DMA controller.

And this is what I have calculated:

CPU takes 1/104 sec to transfer this data while the DMA controller takes 1/417 sec. Clearly the DMA is faster but the question says that it should be slower. What am I doing wrong here?

Ayaz Ahmed Ayaz Ahmed · Accepted Answer · 2019-01-29T13:14:55

The performance of a 2MHzCPU is calculated as 2 MIPS. Data Transmission speed of a

scanner is calculated as 9600 bytes per second. Direct Memory Access (DMA) controller 

 transfers 16-bit data from scanner to memory in  one clock cycle using cycle stealing. 

 If such a controller is attached with a  system, then calculate the percentage of speed dropped

  by using DMA controller.

DMA Controller vs CPU

1 Answers