I have some older documentation that indicates that Tops-20 did DECnet over X.25.  The NCP will still allow for X.25 to be defined as a type for a circuit.

I would have to assume that this traffic would be handled by a DN20 running some version of MCB.  About two years ago, I had done some work on the DTE driver (DTESRV) to eliminate DTEKPA BUGCHK's which can occur on really fast machines with very low device latency during times of heavy I/O and computation.

There is plenty of code in there to handle various flavors of DN20's: RSX20F front ends, MCB based DECnet DN20's and DN60 bi-synchrounous communications.  I don't immediately recall seeing anything specific about X.25.

Has anybody ever heard anything about a 20 doing anything with X.25?

On 8/25/22 7:30 AM, Trevor Warwick wrote:
Great, feel free to email me if you need any help with getting it going.   I haven't yet tried it out with a Phase IV P.S.I. setup. In that case one would use UEDRIVER for the DPV11 and X-something-DRIVER for the DUP, but I don't know whether I did enough in open-simh to allow those to work - they may rely on some nuance of the device behaviour that hasn't been tested.

I'm not aware of any X.25 network simulator, so I think a back to back configuration is all that can be tried currently. 

Trevor



On Thu, 25 Aug 2022 at 11:57, Peter Allan <petermallan@gmail.com> wrote:
This is exciting. I will try this out.

I have been wanting to set up an X25 system for ages, mainly because we used X25 to link computers on the UK JANET network back in the 1980s when I was a manager of a VAXcluster. We ran DECnet over that X25 link as well as other protocols.

Do you know of any public domain software that simulates an X25 network that it might be possible to use to connect two or more simulated VAXen running P.S.I.? The ideas I have found on the internet never seem to have reached the stage of implementation.

Cheers

Peter Allan

On Thu, 18 Aug 2022 at 15:12, Trevor Warwick <twarwick@gmail.com> wrote:

I recently added HDLC framing support to the DUP11 and DPV11 devices in open_simh. This has only so far been tested with DECnet-Plus on VMS.  

I wrote up another couple of examples, showing how to use HDLC as a DECnet datalink, and also how to try a basic configuration of VAX P.S.I. for X.25 communication.


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