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ADDRESSING MODES S3C9228/P9228
3-10
DIRECT ADDRESS MODE (DA)
In Direct Address (DA) mode, the instruction provides the operand's 16-bit memory address. Jump (JP) and Call
(CALL) instructions use this addressing mode to specify the 16-bit destination address that is loaded into the PC
whenever a JP or CALL instruction is executed.
The LDC and LDE instructions can use Direct Address mode to specify the source or destination address for
Load operations to program memory (LDC) or to external data memory (LDE), if implemented.
Sample Instructions:
LDC R5,1234H ; The values in the program address (1234H)
are loaded into register R5.
LDE R5,1234H ; Identical operation to LDC example, except that
external program memory is accessed.
dst/src
OPCODE
Program Memory
"0" or "1"
Lower Address Byte
LSB Selects Program
Memory or Data Memory:
"0" = Program Memory
"1" = Data Memory
Memory
Address
Used
Upper Address Byte
Program or
Data Memory
Figure 3-10. Direct Addressing for Load Instructions