The zip includes all of the source as well as the executable
and the help file, which are the only two you really need. 

Be sure to install the help file in a path where Windows and
the executable itself can find it.

Lots of comments in the source file.

RGM

PS. If you're using a pre-NT version of Windows then
be aware that the code which reads/writes to raw devices
(like a CF card) is untested on these older operating
systems. If it works, it will need a third file, 
INT13EXT.VXD, to be available to the executable.