This addressing mode specifies that the operand is in one of the
data registers.
Mode:\b 000 \bRegister: register number 0 through 7
Assembler Syntax: Dn
Format:
\i11X,1X,1X,1X,1X,1X,1X,1X,1X,1X,u6Effective Address,3Mode,3Register,
.000201