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ADDRESSING MODES S3C9228/P9228
3-6
INDIRECT REGISTER ADDRESSING MODE (Concluded)
dst
OPCODE
4-Bit Working
Register Address
Sample Instructions:
LCD R5,@RR6 ; Program memory access
LDE R3,@RR14 ; External data memory access
LDE @RR4, R8 ; External data memory access
Program Memory
Register File
src
Value used in
Instruction
OPERAND
Example Instruction
References either
Program Memory or
Data Memory
Program Memory
or
Data Memory
Next 3 Bits Point
to Working
Register Pair
(1 of 8)
LSB Selects
Register
Pair
16-Bit
address
points to
program
memory
or data
memory
CFH
.
.
.
.
C0H
Figure 3-6. Indirect Working Register Addressing to Program or Data Memory