Think your remembering MS-DOS running machines.
https://en.wikipedia.org/wiki/AmigaOS
https://en.wikipedia.org/wiki/Atari_TOS
Sadly the wrong MS Operating system won out cause ya business. Not faulting MS for pushing their own thing either... don't get me wrong. At&T screwed themselves. (or the gov screwed us all when they broke up bell... making their software division an important revenue generator)
https://en.wikipedia.org/wiki/UNIX_System_V
There was a time when everyone not IBM was betting on another path.... versions of System 4 was found on Ataris, Amigas, Apples, Sony, Sun ect. Companies like Atari even had Unix S5 shipping units for awhile powered by very nice hardware.
Believe it or not at one point the majority of Unix running computers in the world where running the system 4 complaint Xenix.
https://en.wikipedia.org/wiki/Xenix
Its really too bad that when AT&T and Bell where broke up in the early 80s that the software division ended up being looked at as a revenue generator in a new way. They where happy to licence everything to MS prior... but at that point AT&T started selling their own system V OS. MS really didn't have much choice but to go their own way and abandon xenix. Thus was born IBM/MS OS/2 project... from which came NT and every version of windows since. If only when the Bell break up happened open source had been what it was today. I imagine today it would have ended up being spun out into something like the Linux foundation. If that had happened. "windows" would never have happened... and we would all likely be running Unix system 8 or 9 complaint Operating systems at this point. (perhaps even from multiple PC vendors... imagine Ataris and Commadores running MS Xenix 10) lol
Alt Universe stuff.... lol one where updates didn't break everything and BSOD would be a strange combo of keys to typo and nothing more.
There was Amiga Unix for the A3000.
https://en.wikipedia.org/wiki/Amiga_Unix