Windows 1.0 BYTE demo

The earliest build of Windows confirmed to exist was shown in the December 1983 issue of BYTE Magazine. It had an interface similar to Word, Multiplan, and Chart for DOS. It is unknown exactly when the build itself was compiled, but it might have been compiled shortly after the release of the Microsoft Mouse. It remains unleaked as of 2013. A similar UI is found in Microsoft Word for DOS 1.0.