You got it wrong (your first sentence), WinNT3.1 is written from scratch by Dave Cutler and his group from 1989 to 1994. Originally there would have been a OS/2

You got it wrong (your first sentence), WinNT3.1 is written from scratch by Dave Cutler and his group from 1989 to 1994. Originally there would have been a OS/2 compatible subsystem, and some ideas stem from OS/2 but NT has a lot of more similarities with VMS, the previous OS project of Mr Cutler at DEC.