Memory Data Register

The memory data register ( MDR) is a register of the CPU and contains the data to be stored in the RAM or read from RAM.

It therefore acts as a buffer that holds the data until it is stored via a control signal to the RAM or placed on the bus. To specify which address the main memory to read / write the MDR, the address is written to the MAR (Memory Address Register ).

In the strict sense it is not so much a real register but rather a passive buffer.

• Computer Architecture