So maybe being a bit pedantic here, but the Atari ST was originally going to use CP/M 68k, but part way through development they changed the base OS from that t

So maybe being a bit pedantic here, but the Atari ST was originally going to use CP/M 68k, but part way through development they changed the base OS from that to what was more of a MS-DOS clone (which as others have said was also mainly a CP/M 80 clone). I think this was done to have better compatibility with the GEM layer, so the Atari ST OS, TOS, was more like MS-DOS than CP/M. It would be interesting to port TOS (or more likely EmuTOS) to this 68k IBM PC and kind of go full circle.