Altirra and illegal opcodes..

[andym00]

I'm getting my hands dirty with the A8s for the first time, and I've just run into the fact that I'm getting Illegal instruction errors from Altirra running my code, when I use illegal opcodes..

 

CPU: Illegal instruction hit: 23AD
(10559:249,108) PC=23AC A=FD X=E0 Y=00 S=F8 P=B5 (N  I C)  23AC: CB               bad

 

The opcode in question is SBX (also called AXS and SAX as well depending upon which side of the fence you hail), which is listed as being present on the 6502C on this this webpage..

 

The CPU model in Altirra is set to 6502C, and the 'Enable Illegal Instructions' box is ticked..

 

Is there something I've missed in the configuration maybe ? Or possibly that I've missed something really obvious here ?

 

Just for reference, and to ensure it's not the assembler ballsing it up, I took exactly the same file, assembled it for a C64 and ran it no problems, so my monies on me missing something glaringly obvious, or Altirra is having a bad day..

 

And the code runs fine if I replace the illegals with regular but slower work arounds..

 

edit: Aha, it works fine in Atari800Win Plus..

Edited September 10, 2009 by andym00