São registradores utilizados em operações com a memória principal
MATR (memory address transfer register). MRR (memory retrieve register).
MAR (memory address register). MBR (memory buffer register).
MAR (memory actual record). MBBR (memory buffer branch register).
MRA (memory register assign). MBAR (memory buffer access register).
MAR (memory adjust register). MVLR (memory virtual linkage register).