Microprocessor
If the number of address bits in a memory is reduced by 2 and the addressability is doubled, the size of the memory (i.e., the number of bits stored in the memory)
While the microprocessor is executing a program an interface circuit takes over control of address, data, control buses when not in use by microprocessor
Data transfer takes place between the I/O device and memory during every alternate clock cycle
The DMA control waiting for the microprocessor to finish execution of the program and then takes over the buses
DMA controller taking over the address, data and control buses while a block of data is transferred between memory and I/O device