Although this OS is the basis for the kernel that all modern versions of Windows currently are based on, this was a major sea change for the platform, and it had a rocky start. Initially started as a re-write of the OS/2 3.0 operating system that IBM and Microsoft collaborated on, the two companies parted ways, and Microsoft decided to take Windows NT in its own direction, hiring Dave Cutler from DEC, the architect of the VMS operating system, to run the core development team. While the OS shared an identical Windowing interface with Windows 3.1, the popular business version of Windows that ran on top of DOS, the two systems were extremely different architecturally.
Windows NT was a native protected mode, multiprocessor-capable, multithreaded, multiuser, processor architecture-independent, true preemptive multitasking OS, but it needed to run Win32 apps written specifically to take advantage of those features. 16-bit Windows apps from Windows 3.1 could run on it, but they ran slowly and not very well -- and DOS compatibility was horrible. In addition, Windows NT 3.1 was expensive (the workstation version was $500), had substantial minimum hardware requirements for the time (a 386 processor and 12MB of memory), and ran best on non-Intel systems such as DEC Alpha and the MIPS.