The Memory Address Register (MAR) is a CPU register that either stores the memory address from which data will be fetched to the CPU or the address to which data will be sent and stored.
In other words, MAR holds the memory location of data that needs to be accessed. When reading from memory, data addressed by MAR is fed into the MDR (memory data register) and then used by the CPU. When writing to memory, the CPU writes data from MDR to the memory location whose address is stored in MAR.
The Memory Address Register is half of a minimal interface between a microprogram and computer storage. The other half is a memory data register.
Far more complex memory interfaces exist, but this is the least that can work.
Famous quotes containing the words memory, address and/or register:
“All water has a perfect memory and is forever trying to get back to where it was.”
—Toni Morrison (b. 1931)
“Another success is the post-office, with its educating energy augmented by cheapness and guarded by a certain religious sentiment in mankind; so that the power of a wafer or a drop of wax or gluten to guard a letter, as it flies over sea over land and comes to its address as if a battalion of artillery brought it, I look upon as a fine meter of civilization.”
—Ralph Waldo Emerson (1803–1882)
“In 1872 I received a request like this and I did register and vote, for which I was arrested, convicted and fined $100. Excuse me if I decline to repeat the experience.”
—Susan B. Anthony (1820–1906)