Thanks, but I meant something even more unpredictable, which is hinted at in your document: "ANE [...] is chip- and/or temperature dependent" and "can not be re

Thanks, but I meant something even more unpredictable, which is hinted at in your document: "ANE [...] is chip- and/or temperature dependent" and "can not be reproduced in visual6502, which hints on it being some analogue side effect that the simulation does not cover". It's a shame that I cannot find the other article, because I remember that the author actually had looked at the individual transistors, and figured out the bus conflict or whatever it was, which pretty exactly described what happened, and maybe even why some bits would be more "weak" than others. EDIT: Oh, hah! Your PDF actually links to it in the same section. The wiki seems currently down, but here's an archive.org link of the page that describes the unstable opcode in great detail. So thanks a lot! https://web.archive.org/web/20210405071521/http://visual6502.org/wiki/index.php?title=6502_Opcode_8B_(XAA,_ANE) https://web.archive.org/web/20210405071521/http://visual6502...