In 1981 with the purchase by Microsoft of the operating system QDOS, which after making a few modifications, becomes the first version of the Microsoft operating system, called MS-DOS 1.0 ( MicroSoft Disk operating System). From here, there are a number of modifications of the operating system, up to the version 7.1, from which MS-DOS ceases to exist as such and becomes an integrated part of the operating system Microsoft Windows. There are huge software include games, programs and applications to suppert it. Now you can download it and run in your computer with the emulators and roms set.