Advanced Embedded Systems Question:

☛ Direct memory access is mainly used to overcome the disadvantages of interrupt and progam controlled I/O.
☛ DMA modules usually take the control over from the processor and perform the memory operations and this is mainly because to counteract the mismatch in the processing speeds of I/O units and the procesor. This is comparatively faster.
☛ It is an important part of any embedded systems,and the reason for their use is that they can be used for bursty data transfers instead of single byte approaches.
☛ It has to wait for the systems resources such as the system bus in case it is already in control of it.