IBM PC Connecting to DECNET

Bill Degnan billdegnan at
Wed Jun 1 23:11:39 CDT 2022

> > > ...
> > > I believe the DEPCA was based on the venerable
> > > SONIC chipset, but it may have been the LANCE. It wasn't NE-2000
> > compatible
> > > (that came later) :).
> >
> > LANCE seems plausible, or perhaps one of the later chips designed by DEC
> > Jerusalem (SGEC etc.).  What's a SONIC?
> >
> SONIC was NatSemi part that a lot of workstations of the early 90s used. It
> does post-date LANCE by a few years.
> > The non-LANCE non-DEC Ethernets I remember are in the DEUNA (no idea
> > what), QNA (Fujitsu???) and CNA (Intel 82586, *groan*).  The LANCE was
> > designed well, with a fair amount of DEC input, and the subsequent
> > internally produced chips were constructed along similar lines.  Once DEC
> > learned  how to make them at not quite insane cost, they became a very good
> > choice and were generally used in DEC products.
> >
> The LANCE and its children were nice chips.
> There's several DEPCAs for 8-bit ISA on ebay for about $50 (and a couple
> for a lot more), and as others have pointed out it is a variation of the
> Am7990.
> Warner

I found two in my inventory of related controllers.  AM7990DC/80

When I added more RAM to the system to bring up to 512K and installed
the DEPCA controller I was able to get the system to boot up and run
the connection scripts that search for a DEC network and associated
services.  Alas, the network is long gone....I would have to attempt
to recreate it!

Anyway, I love that I was able to learn at least how a PC might be
configured for such work.  It would not be impossible at all to
connect this PC to a VAX 4000 driven DECNET by editing the script with
the correct names and services on both ends.

Anyone here doing this kind of thing?


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