Very nice. I think the PDP11, 6800 and certainly the Z80 also have automatic sign extension in some instructions under certain circumstances. Is this emulated correctly in Steem\SainT and Hatari?
Still got, still working: Atari 4Mb STe, 520STFM, 2.5Mb STF.
Hardware: Cumana CSA 354, Ultimate Ripper, Blitz Turbo, Synchro Express II (US and UK Versions).