Board 2
 Says Digicard D-Net and has a wire that goes to a board in slot 1. 
biggest chip is
an am8530h-
  6pc 
 THe 8530 is a complex sync/async serial chip IIRC. It's the one used in
 the Macintosh, etc. This could be some kind of network card (based on the
 name), although it may well not use any well-known protocol.
 
 
Bet this is an appletalk network card.  Rare birds, those.