[HECnet] DMC11 in next simh version... looks nice, and question about TOPS-10

[Cory Smelosky]

On 2 Jan 2013, at 16:33, Jordi Guillaumes i Pons <jg at jordi.guillaumes.name> wrote:

Hello,

The upcoming SIMH version (4.0) comes with a virtual DMC11. It has been merged to the head branch in the git repository, so I have been playing with it a little bit. The simh team has done an aswesome work again, so kudos for Bob, Mark and all the others... It seems the DMCx are supported in pdp10, pdp11 and the VAXen. The basic instructions to make it work are in the DOC files. Just to make the story short:

- DMC11s work in pairs, just like the real devices.
- One of the DMCs has to be put in PRIMARY mode, the other one in SECONDARY. The default is SECONDARY.
- Each of the DMCs has to be attached to a local port.
- Each of the DMCs has to be peered with the remote port.

Let's say we have a VAX780 running at 10.0.0.1 and another one running at 10.0.0.2. To link both simulators via DMC11s we have to:

In 10.0.0.1 INI file:

simh> set dmc0 enable
simh> set dmc0 peer=10.0.0.2:22222
simh> att dmc0 11111

In 10.0.0.2:

simh> set dmc0 enable
simh> set dmc0 linemode=primary
simh> set dmc0 peer=10.0.0.1:11111
simh> att dmc0 22222

Then, in both systems, once VMS is running:

NCP>define line dmc-0 state on
NCP>define cir dmc-0 state on cost 5
NCP>set line dmc-0 all
NCP>set cir dmc-0 all

(The systems must be routers if they also use the ethernet circuit)

In a few seconds, the circuit will go up and the adjacency will come alive.

Thank you for this information.


So we have now an alternative way to link our HECnet nodes via internet. The problem is the link has to be defined in both machines (so it does not help road warriors, a VPN link is still required). It uses TCP links, but if the IP link goes down it is smart enough to reconnect when it comes up again. According to the comments in the code it seems there are plans to add UDP transport. It would be even nicer if it could emulate somehow the multinet tunnel protocol :) but.

How is the performance?


Now the question. It seems the DMC11 device is supported in the KS10 emulation. Could it be posible to use it to DECNETize (and HECNETize) TOPS-10 over simh? I have not been able to find the docs to install DECNET-10 in a 7.04 monitor... Any TOPS-10 hacker around? :)