Suppose that a processor can address directly up to 4 Gigabyte main memory and can operate words with size 32 bit. Find how big should be the size of the "MAR" (memory address registers), "MDR" (memory data registers) and accumulator registers in this computer?
My answer: MDR is 32 bit wide since it exchanges data not only via the data bus but with the CPU data registers. How about MAR and accumulator? how are they related to the 4 gigabyte main memory?