To build Emacs from source for MS-DOS, see the instructions in the file msdos/INSTALL in the distribution. The DOS port builds and runs on plain DOS, and also on all versions of MS-Windows from version 3.X onwards, including Windows XP and Vista.
The file etc/PROBLEMS contains some additional information regarding Emacs under MS-DOS.
A pre-built binary distribution of the old Emacs 20 is available, as described at
For a list of other MS-DOS implementations of Emacs (and Emacs look-alikes), consult the list of “Emacs implementations and literature,” available at
Note that while many of these programs look similar to Emacs, they often lack certain features, such as the Emacs Lisp extension language.