Legacy apps in Windows/OS X was Re: Old MS-DOS & Win Software
trixter at oldskool.org
Thu Dec 8 16:24:32 CST 2005
Tony Duell wrote:
>>Chuck Guzis wrote:
>>>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?
> 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.
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
Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/
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