36bit still in use ?

Rich Alderson RichA at LivingComputerMuseum.org
Sun Nov 30 14:03:45 CST 2014

From: Jacob Dahl Pind
Sent: Friday, November 28, 2014 7:26 AM

> On the talk of copyright status on TOPS-10/20 on the hecnet maillist, it 
> was hinted at tops-20 where used embedded for routers from XKL, running on 
> reimplemnted pdp10 hardware.

> <qoute>
> Unfortunately I do not have much details. I was at the Living Computer Museum
> and talked with RIch Alderson, who used to work at XKL. And he showed me a
> newer generation router from XKL, opened up, at LCM. And they use a PDP-10 on
> a chip, and it was actually running TOPS-20, and I could play around at the
> EXEC level in there.
> </quote>

> Findes it somewhat hard to imagine anyone would take 36bit architectur and 
> build a router around it.
> But it does seem posible they really do, I visisted 
> ftp://xkl.com/pub/download/

> tar xvf DarkStar_v3.0.0.tgz
> and looking in upgrade-example.txt

> I sees things as 
> System Processor (XKL-2)
>   2.    XMH-1 (256MW), Testing: SDdAa, on line at LPN o0
> Reading 0704 pages
> 0704000 words read in 36 bit mode

> ..

> Its alive! who would have though that

The Toad-2 processors (each router contains a redundant pair)are not the
routing engines in the DarkStar products from XKL.  Routing at those speeds
(OC-192, 10G Ethernet, etc.) is handled directly at the connector.

However, when a router is powered up, or when configurations are changed,
it is useful to have a real operating system with well known tools available
to make those operations simpler.  This was a felt need as far back as the
SUN boards used on the 3Mbit PUP network created at Stanford before there
as ever a company called cisco Systems (and that was the original spelling).

As the late Mark Crispin was fond of saying, TOPS-20 is a great improvement
on its successors, so the extended PDP-10 architecture of the Toad-1 was
implemented in a Xilinx FPGA, with further extensions to the OS, and the
Toad-2 came into being.

NB:  I worked at XKL for 10 years before coming to my present job 11 years
ago.  Putting the Toad-1 into an FPGA was an experiment when I left.  I was
ecstatic to learn of the success of the Toad-2 a few years later, but not
really surprised.


Rich Alderson
Vintage Computing Sr. Systems Engineer
Living Computer Museum
2245 1st Avenue S
Seattle, WA 98134

mailto:RichA at LivingComputerMuseum.org


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