Ron. Where did the back ncp come from?as I said I never saw it and we tried to find one.  Same for an IP implementation.  That's why we wrote one.  We were 3coms first customer and I somewhere have the mailing evenlope marked the 32 of December because they had a VC payment dependent on delivering before end of year.

As for 11s. Yes that is true.  A lot of them front ended large systems as Bob pointed out but many were self supporting as you note. 

On Sun, Oct 24, 2021 at 2:41 PM Ron Natalie <> wrote:
There were definitely as many PDP-11's (most running UNIX) as there were DEC 10s in the glory days of the Arpanet.   VAXes only rolled out toward the end of the NCP era.    

However, the last NCP host table shows this statistic for DEC machines on the NCP Arpanet

VAX (UNIX):  58
VAX (VMS):  19

PDP11 (UNIX):  59
PDP11 (RSX): 6
PDP11 (MOS):  11
PDP11 (MINITS); 10

PDP10 (TOPS-20):  40
PDP10 (TOPS-10): 7
PDP10 (TENEX):   22
PDP10 (ITS):  4
PDP10 (WAITS): 3

I had all but forgotten about Local Host / Distant Host / Very Distant Host 1822 protocols.    I remember that BRL had a PDP-11/40 running ANTS (ArpaNet Terminal Server out of University of Illinois).   It got replaced by an 11/34 running UNIX when the Arpanet went to long leaders New Years 1981.
Sent from a handheld expect more typos than usual