
MB90560 series
APPENDIX B INSTRUCTIONS
493
G
Direct addressing (addr16)
Operand values specify lower 16 bits of an memory address directly. Address bits 16 to 23 are
specified by the DTB register.
Prefixed instructions that specify the access space are invalid for this type of addressing.
Figure B.3-7 shows an example of direct addressing (addr16).
Figure B.3-7 Example of direct addressing (addr16)
G
I/O direct bit addressing (io:bp)
This method directly specifies bits within the physical address range from 000000H to 0000FFH.
The bit location is expressed as :bp, with higher values representing a more significant bit (MSB)
and lower values representing a less significant bit (LSB). Figure B.3-8 shows an example of I/O
direct bit addressing (io:bp).
Figure B.3-8 Example of I/O direct bit addressing (io:bp)
G
Condensed direct bit addressing (dir:bp)
This method uses the operand to specify the lower eight bits of the memory address. Address
bits 8 to 15 are specified by the DPR register and address bits 16 to 23 are specified by the DTB
register.
The bit location is expressed as :bp, with a higher value representing an MSB and a lower value
representing a, LSB. Figure B.3-9 shows an example of condensed direct bit addressing
(dir:bd).
After execution
Before execution
Memory space
Memory space
SETB i:0C1H:0 (Instruction that sets a bit using I/O direct bit
addressing)