Not quite correct... There is a Trumpcard 500 "AT" as well, which is a totally different board for the A500, with SIMM sockets and an IDE interface, instead of SCSI, and the .dms in the link you provided is for this one...
When I start up the program I get an error message "Unable to find Trumpcard 500 AT" ( Notice th "AT" ) and the program shuts down. If I fool around a little with the settings, the program doesnt display the error message and starts up, but it doesnt display the hard drive connected to the controller...
I´m not quite sure how to use hdtoolbox together with this device...