The following is quoted from Chen Mo at 2004-2-19 21:09:15:
I just took a rough look at the Windows 2000 source code,
and my preliminary judgment is that Wengier's view:
OS/2 + graphical interface
is correct.
This has long already been an ironclad fact...
The WinNT series was modified from OS/2 1.2
At the time M$ and IBM cooperated to launch a fast 32-bit operating system, which was OS/2...
M$ also released its M$ OS/2 1.2
After that M$ no longer cooperated with IBM to make OS/2, and changed its original source code (from the kernel to the file system and executable file format)
into Win NT 3.1
After that the Chicago project was launched, and M$ also released a Chicago-interface test version of 'New Shell for Win NT 3.51' for Win NT 3.51
At this point OS/2 formally split from Win NT