Morgan Olsson wrote:


>Yes, the solutions below are a smart way to always have carry bit to tell
>if we had an overflow.
>
>Only problem is that in case when the add/sub of the lower byte resulted in
>a carry that made the inc/dec to wrap: the high byte does not get
>added/subtracted!  (or am I just too tired this late on a friday?)

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Yes, the only time the last add or subtract is skipped is when the value to
add or subtract is zero. The carry bit and the 16-bit results are both
correct in all cases.

Chip.