Could I attach two PC motherboards (ISA? PS/2? PCI?
EISA? NuBUS?
Others?) together via a ribbon cable by the bus connectors and then
transfer data among them, of course having written the approporiate
drivers? 
No.
It's not PS/2, it's MicroChannel Architecture.  NuBus isn't PC, it's Mac.
                        Zane
| Zane H. Healy                    | UNIX Systems Adminstrator  |
| healyzh(a)ix.netcom.com (primary)  | Linux Enthusiast           |
| healyzh(a)holonet.net (alternate)  | Classic Computer Collector |
+----------------------------------+----------------------------+
| For Empire of the Petal Throne and Traveller Role Playing,    |
| see 
http://www.dragonfire.net/~healyzh/                       |
| For the collecting of Classic Computers with info on them.    |
| see 
http://www.dragonfire.net/~healyzh/museum.html            |