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APPENDIX B Instructions
●
Abbreviated direct addressing (dir)
Specify the eight low-order bits of a memory address explicitly in an operand. Address bits 8 to 15 are
specified by the direct page register (DPR). Address bits 16 to 23 are specified by the data bank register
(DTB).
Figure B.3-6 Example of Abbreviated Direct Addressing (dir)
●
Direct addressing (addr16)
Specify the 16 low-order bits of a memory address explicitly in an operand. Address bits 16 to 23 are
specified by the data bank register (DTB). A prefix instruction for access space addressing is invalid for
this mode of addressing.
Figure B.3-7 Example of Direct Addressing (addr16)
4 4 5 5
1 2 1 2
6 6
6 6
? ?
1 2
4 4 5 5
1 2 1 2
7 7DTB
7 7
DTB
776620H
776620H
Before execution
After execution
MOVW S;20H, A
Memory space
Memory space
A
A
(This instruction writes the contents of the eight low-order bits of A in abbreviated
direct addressing mode.)
2 0 2 0
A
0 1
DTB
553B21H
2 3
553B20H
MOVW A, 3B20H
Before execution
After execution
Memory space
(This instruction reads data by direct addressing and stores it in A.)
A A B B
A
5 5
DTB
A A B B
0 1 2 3
5 5