
Table 2-2 Effective Address Calculation
Addressing Mode and
Instruction Format
op
rm
7 6
3
4
0
15
No.
Effective Address Calculation Method
Effective Address (EA)
1
Register direct, Rn
Operand is contents of registers indicated by rm/rn
Register indirect, @Rn
Contents (16 bits) of register
indicated by rm
0
15
Register indirect with displacement,
@(d:16, Rn)
op
rm
rn
8 7
3
4
0
15
op
rm
7 6
3
4
0
15
disp
op
rm
7 6
3
4
0
15
Register indirect with
post-increment, @Rn+
op
rm
7 6
3
4
0
15
Register indirect with pre-decrement,
@–Rn
2
3
4
Incremented or decremented
by 1 if operand is byte size,
and by 2 if word size
0
15
disp
0
15
0
15
0
15
1 or 2
0
15
0
15
1 or 2
0
15
rm
3
0
rn
3
0
Contents (16 bits) of register
indicated by rm
Contents (16 bits) of register
indicated by rm
Contents (16 bits) of register
indicated by rm
23