[HECnet] DECnet Phase I and II

[G.]

Hello everyone,

some recent messages about past DECnet Phases led me to do some research about
older Phases features and facilities. If I'm not wrong, and with a little bit
of oversimplification, I would say that Phase III is like Phase IV without
areas and just 255 nodes (and anything but DDCMP at data link level), but the
overall end-user functionality should be almost the same as Phase IV. Right?

But what about Phases I and II?

I've read that some Phase II implementations could be configured to run an
intercept function that would allow for simple star-shaped networks, with the
"interceptor" node acting as a central switch among at most 32 satellite nodes
(not to be confused with cluster satellites). But how that worked? I've also
read that DECnet "poor man's routing" had its birth just in Phase II days, so
was PMR needed to route messages thru the central node when sending from one
satellite to another, or was that automatic and PMR was needed only when stars
where connected together by their central nodes (if that was possible at all)?

Then, speaking about Phase I, was it strictly a point to point two-node thing
or some sort of "chaining" was available thanks to PMR?

That's all. Many thanks to who will shed some light on this topic,

G. :)