Oops, "real-mode" dos made me think native DOS. If you are running in a window on windows you just need to use the windows version of brltty, http://brl.thefreecat.org/brltty/brltty-win-4.0-2.zip for a portable version or http://brl.thefreecat.org/brltty/brltty-win-4.0-2.exe for an installer version. Samuel