[HECnet] Tops-20 ANONYMOUS FAL Preliminary Testing Results/DAP Query

Was 11/D what also ran in DN20's?? The DECSYSTEM-20 was actually a cluster of computers with the PDP-10 being connected to up to four 11/40's (or 34?) via interfaces called DTE's.? The DN20 was a repackaged PDP-11 (34?) and they were incredibly useful. CU20B, our largest system, had three such units: 1. Front-end PDP-11, ran a variant of RSX called 20F and handled communications lines, unit record equipment and (I believe) the AN20 ARPAnet IMP interface. 2. DECnet DN20; we had lines to other 20's (KMC11's) before we got Ethernet, plus a line to a VAX and a DN200 RJE. 3. DN65, used for IBM/HASP communications.? I had source to the DN65, but I can not remember for the life of me whether it was an RSX variant or custom code.? That's surprising because I had to make some modifications to have it talk with one of our 4341's. I have heard a site (I believe it was Case Western) that had a fourth PDP-11 serving as a communications concentrator for more lines (DH11's).? One shudders to think of a 20 with that many users.? Things got pretty slow at 50 and once you got up to 70, it was time to find something else to do.