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APPENDIX B Overview of Instructions
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Relative addressing
Relative addressing is indicated by rel in the instruction list. This addressing is used to branch to within the
area between the address 128 bytes higher and that 128 bytes lower relative to the address contained in the
PC (program counter). In this addressing mode, the result of a signed addition of the contents of the
operand to the PC is stored in the PC. Figure B.2-9 "Example of relative addressing" shows an example.
Figure B.2-9 Example of relative addressing
In this example, a branch to the address of the BNE operation code occurs, thus resulting in an infinite
loop.
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Inherent addressing
Inherent addressing is indicated as the addressing without operands in the instruction list. This addressing is
used to perform the operation determined by the operation code. In this addressing mode, different
operations are performed via different instructions. Figure B.2-10 "Example of inherent addressing" shows
an example.
Figure B.2-10 Example of inherent addressing
9AB AH
BNE F EH
Current PC
9AB C
H
Previous PC
9ABCH + FFFEH
9 A B DH
NOP
9 A B CH
Current PCPrevious PC