First of all, did MS Xenix run on PC hardware? Yes, 286 and above as I recall. Introduced August 1984. Secondly, was there ever a Windows NT 1.0 and 2.0? In a sense, this was OS/2. OS/2 1.x was a cooperative venture between Microsoft and IBM, with the majority of the OS/2 core designed by MS architect Gordon Letwin (ref: the 80s book _Inside OS/2_ by Letwin, MS Press). The first version of Windows NT, 3.1, arose from a difference of opinion between Microsoft and IBM over the future of advanced operating systems; a difference of opinion created by the huge unanticipated success of Windows 3.0. After the Win3.0 release, IBM and Microsoft development paths diverged, with IBM focusing on OS/2 2.x, and Microsoft on Windows 3.x. Both continued work on their 3.0 releases of advanced operating systems, which became OS/2 Warp and Windows NT respectively. Kai My opinions not Microsoft's, etc.