What was the original name of Microsoft Windows before its release?

Microsoft Windows was briefly called “Interface Manager” before its release. The name described the software’s role as a graphical interface layer for MS-DOS rather than a complete standalone operating system.

Microsoft began developing the project after Bill Gates saw VisiCorp’s Visi On demonstrated at COMDEX in 1982. The company publicly demonstrated an early window manager in September 1983 and announced Windows later that year. During this development period, Microsoft used Interface Manager as the codename.

The project’s identity changed before launch, and Microsoft released Windows 1.0 on November 20, 1985. It ran on top of MS-DOS and introduced tiled application windows, menus, simple graphics, and bundled tools such as Paint and Windows Write. Unlike later versions, Windows 1.0 did not use overlapping windows as its normal interface.

A common mix-up is treating Interface Manager as an official retail product name. It was a development codename; Windows became the public name and continued through every subsequent major release.