[Coco] Bug in VCC ???
Luis Antoniosi (CoCoDemus)
retrocanada76 at gmail.com
Wed Apr 16 14:09:34 EDT 2014
I made a comparison to the MESS. Maybe MESS has it's bug as well.
This was the first difference I found.
On Wed, Apr 16, 2014 at 1:57 PM, William Astle <lost at l-w.ca> wrote:
> On 14-04-16 11:46 AM, Luis Antoniosi (CoCoDemus) wrote:
>> I found VCC does Half-Carry different from 6809.
>> doing this:
>> ldd #$0fc9
>> addb #$40
>> adca #$00
>> it will set the HC on VCC but not on 6809.
> I would have expected the 6809 to actually set H in this case. The
> references I have available say it should. After all, you do have a carry
> from bit 3 to bit 4 during the ADCA.
> Still, the H flag is only used by DAA. I would be surprised if it is the
> problem in this case (unless the code that's failing is using DAA somehow?)
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