On July 27, 1993, Microsoft shipped Windows NT 3.1, the first release of an operating system that had been built from scratch rather than layered on top of MS-DOS. Microsoft’s feature on lead architect Dave Cutler states plainly that “Windows NT 3.1 shipped July 27, 1993, becoming the foundation for all major Windows versions since.”
A 1998 Microsoft press release recounts the project’s origins and design. The company “formed what was to become the development team for Windows NT in 1988 with the goal of developing a thoroughly modern, fully 32-bit, robust, multipurpose operating system.” That same release describes the first products, Windows NT 3.1 and Windows NT Advanced Server 3.1, as featuring “a new micro-kernel operating system architecture, pre-emptive multitasking scheduler, the fault-tolerant file system of Windows NT, multiprocessor support, the 32-bit Windows-based architecture, powerful domain-level security, file and print services, and more.”
NT was designed to be portable across processor architectures, a goal Cutler carried over from his work on VMS at Digital Equipment Corporation. The detailed up-front specification work the team did before coding began in 1989 reflected that engineering discipline.
The release marked Microsoft’s serious entry into enterprise and server computing. Although adoption started small, the press release reports that NT grew “from a modest 34,000 licenses sold in fiscal 1994” into a mainstream platform, and the NT lineage continues under every modern version of Windows.