Posted By
indi
on 2007-04-08
14:19:49
|  Undocumented opcodes....
Okay... I'd assumed that all 6502 docs work on the plus/4, but just found out XAA (Transfer X to A and AND with immediate) doesn't work.
So... is there a list of valid Plus/4 undocumented opcodes?
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Posted By
Gaia
on 2007-04-08
14:21:55
| Re: Undocumented opcodes....
Well, there's a good reference you could use: http://www.oxyron.de/html/opcodes02.html. It is for the C64 but it's just as OK for the plus/4 as far as I can tell. (Is that you, Mike?  )
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Posted By
indi
on 2007-04-08
14:54:11
| Re: Undocumented opcodes....
Ah..okay... it lists the XAA one as unstable, which explains a lot. Might just be that one I guess..
..............and yes
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Posted By
Gaia
on 2007-04-08
16:11:09
| Re: Undocumented opcodes....
Ah, so you have changed handle As for the XAA, I think we have discussed it quite thoroughly a while ago, if you hit the search box I'm sure you'll find the thread(s).
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Posted By
indi
on 2007-04-09
02:12:12
| Re: Undocumented opcodes....
Well, its the old handle I used to go by when I was coding on the +4 and C64, and I reserected it on Lemon64 - so I thought I'd use it here too
Found the old thread. Yep...pretty much what I get as well -although on my Plus4 it just seems to hang. 
Handy opcode as well...dang. Did you ever get round to making a list of codes that actually WORK on the +4/C16?
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Posted By
NinjaDRM
on 2007-04-09
03:54:13
| Re: Undocumented opcodes....
You can also try this:
http://unusedino.de/ec64/technical/aay/c64/ibmain.htm
Everything not marked as instable does work (and I used quite a lot of them). The SHA/X/Y/S instructions are not unstable, by the way, but this has to wait until the next release
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