ASCI u68 (SystemX)

Hey guys, Posting this to various forums in the hopes of finding someone in the know - I have this ASCI u68 system (6800 cpu) that I understand was used in educational environments. I kind of have it running but know little about assembly language programming, etc. Or the unit itself. Have any of you ever messed with these? It looks like it has a serial connector on its mainboard.. was trying to figure out a way if I could patch it to one of my terminals. Also trying to find some simple 6800 assembly programs/routines to test it and see if it really works properly. There is an MC6821S chip on it (there are three of them actually) and one in the middle is marked 'BAD'. I understand those handle peripherals. I'd also heard rumours there was a second board available for these that gave them BASIC. I've never seen such a board for sale anywhere - wondered if anyone had seen one in the wild. Brad