I thought it was the BIOS that was the compatibility issue. That's one of the few proprietary parts IBM had when they released their PC. Clones were built on a

I thought it was the BIOS that was the compatibility issue. That's one of the few proprietary parts IBM had when they released their PC. Clones were built on a reverse engineered BIOS that, for a while, wasn't quite right. I vaguely recall 90% PC Compatible computers or something like that. Halt and Catch Fire covers this. I could be wrong though. https://www.imdb.com/title/tt2543312/ https://www.imdb.com/title/tt2543312/