[HECnet] DECnet for DOS / Rainbow documentation?

[Robert Armstrong]

  I'm just curious - how did the DECnet for Rainbow connect?  The DECnet/DOS that I remember using required a 3Com ISA Ethernet card of some flavor, but AFAIK there was never an Ethernet for Rainbow.  Did DECnet/Rainbow use a DDCMP serial connection?  Or some other magic thing?

  If DECnet/Rainbow is still around I'd like to get a copy.  I have a Rainbow 100B and DECnet would be a nice addition.

Thanks,
Bob