Windows 1.0 is the first major release of Microsoft Windows, a family of graphical user shells and operating systems for personal computers developed by Microsoft. It was first released to manufacturing in the United States on November 20, 1985, while the European version was released as Windows 1.02 in May 1986.
Its development began after Microsoft co-founder Bill Gates saw a demonstration of a similar software suite, Visi On, at COMDEX in 1982. The operating environment was showcased to the public in November 1983, although it ended up being released two years later. Windows 1.0 runs on MS-DOS, as a 16-bit shell program known as MS-DOS Executive, and it provides an environment which can run graphical programs designed for Windows, as well as existing MS-DOS software. It included multitasking and the use of the mouse, and various built-in programs such as Calculator, Paint, and Notepad. The operating environment does not allow its windows to overlap, and instead, the windows are tiled. Windows 1.0 received four releases numbered 1.01 through 1.04, mainly adding support for newer hardware or additional languages.
