Date   : Tue, 14 Mar 2006 07:49:57 +0000
From   : Andy Armstrong <andy@...>
Subject: Re: Web site: Mainly Master 512

On 14 Mar 2006, at 07:10, John Kortink wrote:
>
> LDA #0
> LDY #&FE
> CLC
> .loop
> ADC addr,Y
> DEY
> BPL loop

That stops after one iteration because Y is negative at the start.  
You need something like

LDA #0
LDY #&FF
CLC
.loop
ADC addr-1, Y
DEY
BNE loop

-- 
Andy Armstrong, hexten.net