I've spent more efforts getting NetBSD on former DECnet machines.

The efforts are far more fruitful.

Quoting Johnny Billquist (bqt@update.uu.se):
> On Mon, 29 Jul 2002, David Laight wrote:
> > > What is it you are after?  Why would you need to change MAC addresses?
> > > (the ONLY time I've ever needed it was with an HA/Failover situation).
> > 
> > In order to run decnet???
> > Requires locally administered addresses.  IIRC top 14 bits (after
> > multicast/unicast and locally/globally administerd) are the network
> > and bottom 32 the machine number.
> 
> DECnet addresses are only 16 bits. 6 bit area number, and 10 bit host
> number, all coded in the low 16 bits of the MAC address.
> 
> Linux have a (semi-)functional DECnet nowadays. Is anyone thinking about
> getting DECnet on NetBSD?