376
Increment/Decrement Instructions
Section 5-26
5-26 Increment/Decrement Instructions
5-26-1 BCD INCREMENT – INC(38)
Limitations
DM 6144 to DM 6655 cannot be used for Wd.
Description
When the execution condition is OFF, INC(38) is not executed. When the exe-
cution condition is ON, INC(38) increments Wd, without affecting Carry (CY).
Precautions
The content of Wd will be incremented every cycle if the undifferentiated form
of INC(38) is used. Use the differentiated form (@INC(38)) or combine
INC(38) with DIFU(13) or DIFD(14) to increment Wd just once.
Flags
ER:
Wd is not BCD
Indirectly addressed EM/DM word is non-existent.
(Content of
*
EM/
*
DM word is not BCD, or the EM/DM area boundary
has been exceeded.)
EQ:
ON when the incremented result is 0.
5-26-2 BCD DECREMENT – DEC(39)
Limitations
DM 6144 to DM 6655 cannot be used for Wd.
Description
When the execution condition is OFF, DEC(39) is not executed. When the
execution condition is ON, DEC(39) decrements Wd, without affecting CY.
DEC(39) works the same way as INC(38) except that it decrements the value
instead of incrementing it.
Precautions
The content of Wd will be decremented every cycle if the undifferentiated form
of DEC(39) is used. Use the differentiated form (@DEC(39)) or combine
DEC(39) with DIFU(13) or DIFD(14) to decrement Wd just once.
Flags
ER:
Wd is not BCD.
Indirectly addressed EM/DM word is non-existent.
(Content of
*
EM/
*
DM word is not BCD, or the EM/DM area boundary
has been exceeded.)
EQ:
ON when the decremented result is 0.
Wd
: Increment word (BCD)
IR, SR, AR, DM, EM, HR, LR
Ladder Symbols
Operand Data Areas
INC(38)
Wd
@INC(38)
Wd
Wd
:
Decrement word (BCD)
IR, SR, AR, DM, EM, HR, LR
Ladder Symbols
Operand Data Areas
DEC(39)
Wd
@DEC(39)
Wd
