[Simh] [HECnet] TOPS-20 V4.1 DECnet

[Mark Pizzolato - Info Comm]

On Friday, May 02, 2014 at 7:36 AM, Paul Koning wrote:
On May 1, 2014, at 9:36 PM, Cory Smelosky <b4 at gewt.net> wrote:

On Thu, 1 May 2014, Cory Smelosky wrote:

Looks like there's no DMC on the PDP-10, no DMC OR KDP on the
MicroVAX, and no KDP on the VAX780.

However, the PDP-11 has the DUP.   Looks like I can use that as the go-
between.


Wonderinf if this is an RSTS/E bug...or a simh bug.

Device XK0: does not interrupt - device disabled.

Probably a SIMH limitation.   It   s complaining about the KMC11.   

This is true.

RSTS supports those only for use with the RJ2780 emulator; it doesn   t use them with
DECnet.

The message comes from the hardware scan code, where it looks around the
bus looking for devices and makes them interrupt to learn what vector each
uses.   For the KMC11, it does that by loading a short program into it.   That
only works if the KMC emulation knows how to emulate a KMC well enough
to run that program.   If it emulates a KMC only as a KMC/DUP pair that
speaks DDCMP, this won   t work.

The KMC emulation could be extended to support this command/program, but since the only implementation of KMC functionality is as a KDP and the KDP wasn't supported on the OS (RSTS) which is observing the lacking of interrupting, then the status quo is probably best.

If you want a RSTS system to connect to your Phase III machine, you   ll want
to use a DMC (or DMR/DMP/DMV, they are all roughly interchangeable).   In a
sufficiently recent SIMH, the DMC emulation speaks real DDCMP so it should
talk with a software DDCMP implementation, such as one that uses a DUP.

The DUP has only been tested talking to the KDP and DMC/DMR on RSX.   If someone wants to try on RSTS I'd like to know if any issues are found.

Or, since it doesn   t know sync from async, it will probably talk to a software
DDCMP implementation that uses a terminal interface.

I believe that it should also talk to an OS based DDCMP implementation which uses Async ports.     If someone is willing to test this, I'll work on any kinks which may be found which might inhibit this.

- Mark

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