NEC PD17062 - Manual (Page 46)

46
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PD17062
6.4 NOTES ON USING THE GENERAL-PURPOSE REGISTER
This section provides notes on using the general-purpose register, referring to the following example:
Example
AND RPL, #000B ; RP
←
0000010B
OR RPL, #0100B ;
MOV BANK, #0000B ; BANK0
LD 04H, 32H
Executing the above instructions loads the contents of address 32H of BANK0 data memory into address
24H in the general-purpose register of BANK0.
In the above example, the general-purpose register is allocated in row address 2H of BANK0, so that the
address of the general-purpose register specified in r in instruction LD r, m is address 24H of BANK0. The
data memory address specified in m is address 32H of BANK0. (See Fig. 6-5.)
Note that it is necessary to code an actual data memory address, for example, 24H, as the value specified
in r when using the assembler. In this case, only the low-order four bits are needed as the value for r, so the
assembler ignores value 2H, which is a row address. Thus, executing instruction LD 24H, 32H produces the
same result as executing the instruction in the above example.
If, when using the assembler, the address of the general-purpose register is specified directly in an operand
of an instruction, as shown below, an error occurs.
Instruction that causes an error
LD 04H, 32H ; The address of the general-purpose register is coded as 04.
Most commonly used method
R1 MEM 0.04H ;
M1 MEM 0.32H ; # R1 and M1 are defined as memory-type addresses, and are
LD R1, M1 ; assigned addresses 04H and 32H of BANK0, respectively.
Executing the following instructions produces the same result as executing the instructions in # because
R1 and R2 are assigned the same column address.
R2 MEM 0.34H
M1 MEM 0.32H
LD R2, M1