Getting 4.2bsd to work with subnets

[J.P.O'Broin]

We have recently been given a 2nd hand WhiteChappel UNIX machine (MG-1)
(a British UNIX machine - company now out of business). 
This machine runs 4.2nix, a 4.2bsd copy, and I am trying to link it up
to the Ethernet. We run a class B network (ie. xxx.yyy.zzz.station id), 
and hence we're subnetted. 
I understand that 4.2bsd doesn't understand subnets (and hence there is
no obvious way of setting netmask using ifconfig), but our network is
fairly static, and we want to link to a specific gatway. Can I setup 
the machine for this.

We have tried to do this by setting up /etc/hosts to know about the gateway,
and whilst the machine transmits correctly to the ethernet (well, it shows up
on etherfind on our SUN's as expected), it doesn't seem to understand what
is coming back to it, and hence won't connect. Is this because it doesn't
understand the returning Ethernet address of the (subnetted) machine we
are trying to talk to?

Any help greatfully received.
Jason.
(email : J.P.O'Broin at uk.ac.durham - drop the ' if it causes problems)