Motorola CPU32 Reference Manual page 64

ABCD
Instruction fields:
Register Rx field — Specifies the destination register:
If R/M = 0, specifies a data register
If R/M = 1, specifies an address register for predecrement addressing mode
R/M field — Specifies the operand addressing mode:
0 — the operation is data register to data register
1 — the operation is memory to memory
Register Ry field — Specifies the source register:
If R/M = 0, specifies a data register
If R/M = 1, specifies an address register for predecrement addressing mode
MOTOROLA
4-16
Add Decimal with Extend
INSTRUCTION SET
ABCD
CPU32
REFERENCE MANUAL