KL-10B in DEC-20 [was RE: Who's rewired their house for this hobby?]

Rich Alderson RichA at LivingComputerMuseum.org
Wed Nov 26 13:57:49 CST 2014

From: Jon Elson
Sent: Wednesday, November 26, 2014 10:36 AM

> On 11/26/2014 01:47 AM, Eric Smith wrote:

>> On Tue, Nov 25, 2014 at 7:42 PM, Jon Elson <elson at pico-systems.com> wrote:

>>> On 11/25/2014 02:18 PM, Eric Smith wrote:

>>>> Actually to 13 massive linear regulators on multiple large heat sinks.

>>> There may have been several versions.  The KL10B in a Decsystem 2020
>>> we had

>> A DECSYSTEM-2020 uses a KS10, which has no ECL, and uses a big
>> switching power supply made by third parties. The KL10B was used in
>> the DECsystem-1090, but not in any DECSYSTEM-20 models.

> Not true!  The CPU was, absolutely, a KL10B.  It was in a big orange
> cabinet that was fairly similar in size and shape to a VAX 11/780.  It
> had a PDP 11/40 (I think) in the next bay over as the I/O processor.
> I am not so clear about the exact "DECSystem" designation, but it VERY
> much was a DECSystem 20<something>.  [...]  The label on the front of
> the cabinet said "DECSystem-20" without specifically giving the model
> number.

Only the DECSYSTEM-2020 (with the KS10 processor) expanded on the "20"
in the name.

I believe that the KL10B processor was used in the so-called "Model A"
DECSYSTEM-2040 and the DECsystem-1080.  All the later systems, generically
called "Model B" by the diagnostics and RSX-20F, were the various suffixes
named by Eric, along with some he did not mention.

We have a non-running 1090 here at the museum which is clearly and
unambiguously labeled as a KL10D, as well as a KL10PV (blue 1095) and
KL10PW (orange 2065) which run WAITS and Tops-10 7.04, respectively.


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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