Windows 1.0 is a graphical personal computer operating environment developed by Microsoft. Microsoft had worked with Apple Computer to develop applications for Apple’s January 1984 original Macintosh, the first mass-produced personal computer with a graphical user interface.

Windows 1.0 was released on this day in 1985 as the first version of the Microsoft Windows line. It runs as a graphical, 16-bit multi-tasking shell on top of an existing MS-DOS installation, providing an environment which can run graphical programs designed for Windows, as well as existing MS-DOS software.

Despite positive responses to its early presentations and support from a number of hardware and software makers, Windows 1.0 was received poorly by critics, who felt it did not meet their expectations. Despite criticism, Windows 1.0 proved to be an important milestone for Microsoft, and in computer history in general. Windows 1.0 was officially declared obsolete and unsupported by Microsoft on December 31, 2001.