DTR-1's propietary hd port?

Is the "proprietary" Hard and floppy disk port on Dauphin's DTR-1
truly proprietary? I read in some road warrior magazine that it is an
IDE port.  Even the manual refers to it as a proprietary port for IDE
drives, which strikes me as potentially contradictory.  Does anyone
have the details on this (and pinouts)? I would like to be able to
hook an external IDE drive to it.