8 Dec
2005
8 Dec
'05
10:24 p.m.
Tony Duell wrote:
Is this "half-carry" flag addressable, or is it just something internal? A
quick gander at 808x flags doesn't show a "half-carry" flag, unless I'm
missing
something obvious.
--
Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/
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Chuck Guzis
wrote:
I believe it's a flag indicating a carry from the low nybble to the high
nybble of the accumulator. That is, it indicates a carry out from the low
half of the byte.
It's mainly needed for BCD operations if memory serves. codes. Inspection of the 808x instruction set can
be very illuminiating,
particularly when it comes to arcana like which instructions modify (and
how) the half-carry flag, for example.
The "half-carry flag"? Huh?