[Coco] 6502 to 6809 translation
jekent at optusnet.com.au
Mon Aug 1 08:23:46 EDT 2011
Rather than using Y you might want to use B,
On 1/08/2011 9:02 PM, Phill Harvey-Smith wrote:
> Hi All,
> I'm currently trying to translate some 6502 code to run on the
> Dragon/CoCo, all is prety easy except for one thing, the 6809 doesn't
> appear to have one of the 6502 indexed modes namely :
> asume that data_addr contains $8000
> and y=$20
> lda (data_addr),y
> which will IIRC take look in data_addr, find $8000 and load a from
> $800+$20 = $8020.
> the 6809 has
> lda (data_addr,y)
> but this will load a from where data_addr+$20 points to, which is not
> the same thing !
> So is there an easy way of translating the 6502 code in a couple of
> 6809 instructions ?
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