IIRC GEMDOS was written more less from scratch by Jason Loveman (last I heard he was at Microsoft). While it's possible he might have cribbed a bunch from the C

IIRC GEMDOS was written more less from scratch by Jason Loveman (last I heard he was at Microsoft). While it's possible he might have cribbed a bunch from the CP/M-68K codebase, it started "in his garage" as a private effort that he hoped he'd be able to sell to someone. DRI wound up acquiring it (I wasn't privy to the terms, I hope Jason got a lot of money, though) and we wound up using it on the ST because absolutely nobody liked CP/M-68K, OMG. I'll have to check out the sources and see if I get the same impression. It's been a while.