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| From: Joe Forster/STA
Date: 2000-07-25
Subject: Re: ADC - SBC
|
Hi Almos!
> 1. What exactly happens when I am trying to add a number to a non-
> decimal coded number (semi-tetrade?) in decimal mode. Like:
>
> LDA #$1e ;Non-BDC
> CLC
> SED
> ADC #$01
>
> What the result would be?
Well, try it! :-) I think, the result will be $1F. Decimal mode kicks in only when you step over or below $A in the lower nybble. For example, $09
+ $01 = $10. But $0A + $01 = $0B.
I suggest that you go to www.funet.fi and grab some documents from there.
One of Marko Makela's great documents explain everything about decimal mode, as far as I remember. (And, no, I don't remember where that document exactly is... ;-) ) Good luck,
Joe Forster/STA sta@c64.org
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