Indirect Addressing Mode
6-15
Addressing Modes

6.3.5 Examples of Indirect Addressing

In Example 6–7, when the ADD instruction is fetched from program memory,

the instruction register is loaded with the value shown.

Example 6–7. No Increment or Decrement
ADD *,8 ;Add to the accumulator the content of the
;data-memory address referenced by the
;current auxiliary register. The data
;is left-shifted 8 bits before being added.
0123456789101112131415
N = No next AR specified
ARU = No operation on current AR
1
Shift = 8
000 0XXX
ADD opcode
0010100 0
Addressing mode = indirect
NAR = don’t cares

In Example 6–8, when the ADD instruction is fetched from program memory,

the instruction register is loaded with the value shown.

Example 6–8. Increment by 1
ADD *+,8,AR4 ;Operates as in Example 6–7, but
;in addition, the current auxiliary
;register is incremented by one, and
;AR4 is chosen as the next auxiliary
;register.
0123456789101112131415
NAR = 4
N = next AR specified
ARU = increment current AR by 1
1
Shift = 8
010 0100
ADD opcode
0010100 0
Addressing mode = indirect