NT has the capabilities to run different API "Personalities". This was pretty major. WIN32 was only one of the APIs NT supported. IBM also did the same with Wor

NT has the capabilities to run different API "Personalities". This was pretty major. WIN32 was only one of the APIs NT supported. IBM also did the same with Workplace OS, but it failed. NT could have been a lot of things, if the competitive landscape was different. From Wikipedia: A main design goal of NT was hardware and software portability. Various versions of NT family operating systems have been released for a variety of processor architectures, initially IA-32, MIPS, and DEC Alpha, with PowerPC, Itanium, x86-64 and ARM supported in later releases. The idea was to have a common code base with a custom Hardware Abstraction Layer (HAL) for each platform. However, support for MIPS, Alpha, and PowerPC was later dropped in Windows 2000. Broad software compatibility was achieved with support for several API "personalities", including Windows API, POSIX,[11] and OS/2 APIs[12] – the latter two were phased out starting with Windows XP.[13] Partial MS-DOS compatibility was achieved via an integrated DOS Virtual Machine – although this feature is being phased out in the x86-64 architecture.[14] NT supported per-object (file, function, and role) access control lists allowing a rich set of security permissions to be applied to systems and services.