Windows 1.01

Windows 1.01 is the first retail release of Windows 1.0, released in stores on 20 November 1985 and discontinued on 31 December 2001. According to Microsoft, Windows 1.01 is an "Operating Environment" designed to run on top of MS-DOS, rather than a standalone operating system. Additional applications were bundled with Windows, including Write (a word processor), Paint (a graphics drawing program), Reversi (a game), and various utilities (Clock, Calendar, Calculator among others).

Windows 1.01 initially retailed for $99 in the US. It is designed to run on MS-DOS 2.00 to 3.31. If it is loaded on MS-DOS 4.00 to 7.10 (without using  on   in MS-DOS 5.00 to 7.10), it will crash on startup. When this happens, it will display a bunch of random symbols on the bottom of the boot screen.