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Increment/Decrement Instructions Section 3-10
The Equals Flag will be turned ON if the result is 0000 and the Carry Flag will
be turned ON when a digit changes from 0 to 9.
Flags
Precautions The content of Wd must be BCD. If it is not BCD, an error will occur and the
Error Flag will be turned ON.
Examples Operation of – –B(596)
In the following example, the BCD content of D00100 will be decremented by
1 every cycle as long as CIO 000000 is ON.
Operation of @– –B(596)
The up-differentiated variation is used in the following example, so the BCD
content of D00100 will be decremented by 1 only when CIO 000000 has gone
from OFF to ON.
−1
Wd Wd
Name Label Operation
Error Flag ER ON if the content of Wd is not BCD.
OFF in all other cases.
Equals Flag = ON if the content of Wd is 0000 after execution.
OFF in all other cases.
Carry Flag CY ON if a digit in Wd went from 0 to 9 during execution.
OFF in all other cases.
D00100 D00100
−1
Decrement Decrement Decrement Decrement
Wd: Wd:
Decremented every cycle
while CIO 000000 is ON.
: Execution of − − B(596)
@
−−
B
D00100 D00100
−1
Decrement Decrement
Wd: Wd:
Decremented only
for up-differentiation.
: Execution of @− −B(596)
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