Here's some information about the Datel Comms Link ISA card: 



Comms Link schematic (BSch CE3) 



Comms Link schematic (PNG) 



Comms Link PAL equations 



Comms Link PAL pin assignments 



Comms Link state machine diagram 



For convenience the schematic uses a 24-pin DIP PAL, but the real thing has a 28-pin PLCC part which is described in the pin assignents document.