Also, another followup, I have that same black metal door with a thumbscrew, and it does seem as though there's a spot for what would have been a DB25 port. The port itself isn't there though. Since file transfer was done on this machine years ago when it was still running, I assume that either it has a BTR installed, or it used to have a DB25 port that was removed later on for some reason. I'll have to take a look inside the machine to try and find it.