DOS Mode
1. On a Microsoft Windows or PC computer, DOS Mode is a true MS-DOS environment. For example, early versions of Windows, such as Windows 95 allowed the user to exit from Windows and run the computer from MS-DOS. Doing this allowed older programs written before Windows or computers with limited resources to run a program. Today, all versions of Windows only have a Windows command line, which allows you to navigate the computer through a command line.
2. On an Apple Macintosh computer, you may get a message about DOS Mode when downloading a file or trying to open a file that is not compatible with the Mac OS. For example, executable files that end with .exe are not formatted for the Mac OS and can only be run from within Windows. Make sure you're downloading a file meant for Apple users otherwise you will need to run Windows from within boot camp if you expect to run a Windows program.
Also see: MS-DOS