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As an Atari ST user, I was a big fan of the 68k back in the 80s but even I'd have to admit that the 808x architecture made the most sense for IBM to take given

As an Atari ST user, I was a big fan of the 68k back in the 80s but even I'd have to admit that the 808x architecture made the most sense for IBM to take given that it offered continuity with the CP/M S100-bus 8080/z80 machines that were fairly dominant in the nascent "business computing" market at that point. Forking CP/M (cuz let's admit that's basically what PC-DOS was) and offering something similar-but-different to those systems was low-risk. And their original intent in fact was to in fact sell a full-on CP/M machine. FWIW the Atari ST is what you get when you take a CP/M/PC-DOS-style OS and bolt it onto the 68k. Syscalls were basically 1:1 with MS-DOS, and even used an MS-DOS compatible filesystem. But big-endian. If you want to see what an IBM PC built around the 68k would have looked like, that's not far off.

jdswain 4y ago
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.