DMA I-O frees the CPU to do other work while an I-O operation is pending. Using DMA I-O requires more complex controller hardware and more complex bus capability. In addition, there is an operational penalty; that is, a disadvantage that shows up while a DMA I-O operation is in progress.

Explain what it is and discuss its ramifications. Also include in your discussion the conditions that must be met for direct memory access to take place.