7480 datasheet(260/337 Pages) RENESAS

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7480 Group and 7481 Group User's Manual

2-45

APPLICATIONS

Figure 2.9.4 Execution of Decimal Operation

2.9 Notes on Programming

Set D flag to ‘1’

ADC,SBC instruction

NOP instruction

SEC,CLC,CLD instruction

2.9.2 Notes Concerning Decimal Operation

Execution of Decimal Calculations

The ADC and SBC are the only instructions

which will yield proper decimal results in

decimal mode. To calculate in decimal notation,

set the decimal mode flag (D) to ‘1’ with the

SED instruction. After executing the ADC or

SBC instruction, execute another instruction

before executing the SEC, CLC, SED or CLD

instruction.

Note on Flags in Decimal Mode

When decimal mode is selected, the values of three of the flags in the status register (the N, V, and

Z flags) are invalid after the ADC or SBC instruction is executed.

The carry flag (C) is set to ‘1’ if a carry is generated as a result of the calculation, or is cleared to

‘0’ if a borrow is generated. To determine whether a calculation has generated a carry, the C flag

must be initialized to ‘1’ before each calculation.

2.9.3 Notes on JMP Instruction

When using the JMP instruction in indirect addressing mode, do not specify the last address on a page

as an indirect address.

Pages are sectioned every 256 addresses from address 0.

For other notes, refer to each section.

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