ADDRESSING MODES

S3C84E5/C84E9/P84E9

 

 

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.

Program or

Data Memory

Program Memory

Upper Address Byte

Lower Address Byte

dst/src

"0" or "1"

OPCODE

Sample Instructions:

Memory

Address

Used

LSB Selects Program Memory or Data Memory: "0" = Program Memory "1" = Data Memory

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.

Figure 3-10. Direct Addressing for Load Instructions

3-10

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Samsung S3C84E5 user manual Direct Address Mode DA, Direct Addressing for Load Instructions