Re: 6502 illegal opcodes

From: Groepaz <>
Date: Sat, 5 Nov 2011 23:47:36 +0100
Message-Id: <>
On Saturday 05 November 2011, you wrote:
> > yes :) and XAA is long "deprecated" imho, only ppl who know it from
> > the old
> > broken lists call it like that =)
> Which list do you recommend?  I find all of them quite broken.

i think the ones most coders use today are (in this order) and (which actually uses XAA, interesting 

> >> (*) Oh and of course the STX abs,Y and STY abs,X (9e and 9c) insns,
> >> those
> >> are naughty!
> > 
> > SHY and TAS you mean =)
> SHY and SHX.  I simply call them STY and STX, because that is what they
> _are_, they just have a little problem :-)  They weren't left out of the
> opcode map "just because", right :-)
> > those are which i ment - they work perfectly if you
> > make sure nothing else tries to access the bus :) (and unlike ANE,
> > they are
> > sometimes useful)
> The only cycle where they run into trouble are the write cycle, they
> cannot
> be influenced by the data bus, not RDY has no effect.  I think you mean
> something else?

uhm well, i am a software guy so i only know it from programmers point of view 
=) which is "make sure no badline hits while the opcode runs". wether it is BA 
or maybe the adress put on the bus by the vic, or whatever else... you can 
probably tell better than me :)


Foolish man give wife grand piano. Wise man give wife upright organ.

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Received on 2011-11-05 23:00:12

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