Z80:
NorthStar DOS
"Microsoft Stand-Alone BASIC" (DOS used on NEC 8001, 9801?, and
some Okidata machines. "MS-DOS Encyclopedia" mentions it on NCR, but I
have never seen that, and suspect that that might be an error, and refer
to NEC. Coco RS-DOS was a heavily modified variant of it, and it
"inspired" Patterson to use the F.A.T. structure in MS-DOS, (as well as
being the DIR structure in 400K MacDOS))