Windows 1.0 was released on November 20, 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. Its development was spearheaded by the company founder, Bill Gates, after seeing a demo of a similar software suite known as Visi On at COMDEX. 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.

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