RL78/G15 CHAPTER 21 BCD CORRECTION CIRCUIT
R01UH0959EJ0110 Rev.1.10 Page 689 of 765
Mar 7, 2023
CHAPTER 21 BCD CORRECTION CIRCUIT
21.1 BCD Correction Circuit Function
The result of addition/subtraction of the BCD (binary-coded decimal) code and BCD code can be obtained as BCD code
with this circuit.
The decimal correction operation result is obtained by performing addition/subtraction having the A register as the
operand and then adding/subtracting the BCD correction result register (BCDADJ).
21.2 Registers Used by BCD Correction Circuit
The BCD correction circuit uses the following registers.
●
BCD correction result register (BCDADJ)
21.2.1 BCD correction result register (BCDADJ)
The BCDADJ register stores correction values for obtaining the add/subtract result as BCD code through add/subtract
instructions using the A register as the operand.
The value read from the BCDADJ register varies depending on the value of the A register when it is read and those of
the CY and AC flags.
The BCDADJ register is read by an 8-bit memory manipulation instruction.
Reset input sets this register to undefined.
Figure 21-1. Format of BCD Correction Result Register (BCDADJ)
Address: F00FEH After reset: undefined R
Symbol 7 6 5 4 3 2 1 0
BCDADJ
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