> On Jul 17, 2016, at 10:41 AM, Paul Koning <paulkon...@comcast.net> wrote:
>
> ...
> I suppose so. Rumor had it that Phase I only existed on RSX, but it appears
> that there was a PDP-8 implementation as well. Phase II was implemented on
> lots of DEC systems, from TOPS-10 to RT-11 to RSTS/E.
By the way: starting with Phase III, DEC adopted "one phase back"
compatibility. A Phase III node could talk to Phase II; a Phase IV node could
talk to Phase III, all documented clearly in the specifications. (Two phases
back wasn't described or aimed for, though it is not that hard; my
DECnet/Python does Phase IV but talks to Phase II.)
On the other hand, Phase II is not compatible with Phase I; the packet formats
are significantly and it's clear that no attempt was made to deliver
compatibility. I don't know why not, or why that changed later. (Before my
time...)
paul
