It would depend on how big "the whole business" is. I looked in http://elvira.stacken.kth.se/rsts/rsts_80th_birthday.html for a memory refresh. DECnet/E appeared in RSTS/E V6C. That was Phase II -- no routing, DMC/DMR only. For 2 or 3 nodes, that was a useable version. Phase III (single level routing) appeared in V7.1. (That was my project -- first RSTS/E project I worked on if you ignore a week on PIP in the V6B timeframe.) That would serve for installations up to about 250 nodes. DMP/DMV support was added, including multipoint. Ethernet support and DECnet phase IV (level 1 routing and endnode only, no area routing) appeared in V9.3. It took so long because it was hard to convince management to allow the work in the first place. There was a sentiment that Ethernet wasn't interesting for PDP-11s, and/or that no RSTS system lived in a network bigger than a few dozen nodes (so Phase IV wasn't needed). The latter argument may have been valid -- I never did run into any really large DECnet networks apart from the one inside DEC. So anyway... unless you want lots of nodes, or multi-area addressing, Phase III will serve which means V7.1 or later is ok. Oh yes, you do need DDCMP then. Ethernet or Phase IV require 9.3 or later; async DDCMP requires 10.0 or later. paul -----Original Message----- From: owner-hecnet at Update.UU.SE [mailto:owner-hecnet at Update.UU.SE] On Behalf Of Gregg Levine Sent: Tuesday, August 25, 2009 12:10 AM To: hecnet at update.uu.se Subject: [HECnet] What DEC created operating systems support the networking protocol used? Hello! I've managed to track down several examples of the RSTS family of operating systems from DEC. Would any of you have any clew as to which member specifically spoke the networking protocol that we use here to communicate within the whole business? These were of course for the PDP-11. ----- Gregg C Levine gregg.drwho8 at gmail.com "This signature was once found posting rude messages in English in the Moscow subway."