Yes, that is how Pdp10 KS10 and Vax and Rsx and Rsts all interface to the Dmc/Dmr offered layer and for Anf10 on Pdp10 as well. But trying Decnet on bare Dup11 will reveal all. However this will fail on simh: look at the comment in Pdp11_dup.c from Bob: dup DUP11 Unibus/DPV11 Qbus bit synchronous interface This module implements a bit synchronous interface to support DDCMP. Other synchronous protocols which may have been supported on the DUP11/DPV11 bit synchronous interface are explicitly not supported. So the 0,01 % rises to 100% that it will not work as bare sync device -----Original Message----- From: owner-hecnet at Update.UU.SE [mailto:owner-hecnet at Update.UU.SE] On Behalf Of Paul Koning Sent: Friday, 19 November, 2021 17:23 To: hecnet at update.uu.se Subject: Re: [HECnet] ANF10 network --> DN200 (RJE, Decnet) --> should be Ddcmp --> Re:4 --> Cryptic I assume it means that RSX (and RSTS too) lets you use a DMC directly from an application as an I/O device you can open. If so, you get a packet service that lets you transmit whatever packets you want, which will be sent encapsulated in DDCMP protocol. In the RSX case I'd assume that includes support for maintenance mode (in RSTS that isn't supported). paul wrote: Ddcmp layer ... it does present it as a device ...". I do not perceive the connotation. Behalf Of Johnny Billquist Ddcmp --> Re:4 it's software side DDCMP. It does present it as a device to the system on which you can send/receive packets.