MS-DOS (Microsoft Disk Operating System) - operating system created by Microsoft company on the basis of the source code of QDOS (Quick and Dirty Operating System) created by Seattle Computers. It is a version of the DOS operating system designed for IBM PCs. Although MS-DOS is itself a text environment, DOS Shell and early versions of Microsoft Windows were supposed to serve as a graphical overlay for the system. However, the Norton Commander - a file manager written outside Microsoft DOS, using the so-called semigraphics of the DOS text environment - turned out to be more popular than Microsoft's solutions. Apart from that, there were also other programs that were graphic overlays on the system, such as 1dir and XTree. Later versions of Windows (from 3.0 upwards in the line of 9x systems, ending with Millennium Edition) became more and more independent operating systems, creating a separate, own development platform. However, all systems of this line started from the DOS level and were compatible with it backwards. With the advent of Windows 95, Microsoft officially discontinued the development of MS-DOS as a stand-alone operating system; the last standalone version of MS-DOS is number 6.22.
MS-DOS marked as 7, 7.1 and 8.0 is the base on which Windows 9x/Millenium was built, being an integral part of them, and for this reason they were not sold as a stand-alone product. In 1993 Microsoft Windows NT was introduced, where Microsoft for the first time resigned from using MS-DOS as a base for the operating system. Removing MS-DOS from the Microsoft Windows line for home users was a difficult step, because a large part of existing programs at that time, including many games, were designed exclusively for DOS. Therefore, Microsoft maintained two lines of systems: Windows 9x/Windows Millennium Edition (Me) and Windows NT line. In Windows Me, MS-DOS was hidden from the user - without appropriate modifications, it was not possible to run the text environment itself at system startup - while since the Microsoft Windows XP version, operating systems based on MS-DOS are no longer released. Despite its lack in newer operating systems, you can still use some MS-DOS commands after running the command interpreter with the cmd instruction. Most applications written for the MS-DOS operating system in this case, however, will not start or will not work properly, but then you can use the help of emulators such as DOSBox.