What is the KH11-A? (was Re: Differences between the PDP-11/15 and PDP-11/20)

Paul Anderson useddec at gmail.com
Mon Aug 22 03:09:06 CDT 2016

Hi Ethan,

I've seen the M780s before, but its been a while.

The DT03 and DT07 are Unibus switiches.

I have several edited option/module lists I can look up boards for you.
Also a fellow list member just scanned a hardware spare parts list that
could have some relevant info in it. I'm sure he'll be posting it soon.

I can probably help you with the Diablo drive, and maybe the H720 later in
the year.

Have Fun, Paul

On Sun, Aug 21, 2016 at 10:36 PM, Ethan Dicks <ethan.dicks at gmail.com> wrote:

> On Sun, Aug 21, 2016 at 1:53 PM, Noel Chiappa <jnc at mercury.lcs.mit.edu>
> wrote:
> >   http://gunkies.org/wiki/KA11_CPU
> Interesting stuff on the KT11, but tangentally, I've been going over
> my pile of parts (that I've described a few times over the years) from
> an 11/20 I pulled from the dumpster at work 30 years ago.  I finally
> got around to photographing the module handles and inventorying many
> of the boards and I've learned a thing or two and have generated a
> question or two.
> First, the manufacture date for most of the parts is in 1972.  The
> front panel says "11/20", so that all jibes.  I appear to have a CPU
> (more below), an M7800 DL-11 console interface (not the older
> multi-board KL-11), a lot of MM-11 4K core sets, and a happy surprise
> (again, more below) and not much else from that extraction (no
> bootstrap card, for example, or peripheral adapters).
> Second, many/most of the CPU modules are -YA variants, and the "PDP-11
> Field Guide" mentions that they would be part of a KH11-A.  About the
> only description I can find for what that is, is a single mention (in
> PDP-11_PeripheralsHbk_1973.pdf) of the "large-system capability
> option" related to the DT03-F Unibus switch requirements.  Anyone know
> what this is?  I'm reasonably certain it doesn't matter for my needs,
> but I'm curious.
> Third, the happy surprise is a full set of boards for a KE11-A.  I
> have been sniffing around for a KE11-B (single-board version), and
> now, I don't need to (as long as this one works or can be repaired).
> This excellent for me since my goal all along has been to fire up
> enough hardware for Warren Toomey's reconstruction of ~1972 UNIX (v1
> kernal plus v2 utilities).  Yes, I know I can run that on SIMH (I
> have), even wrapped up in a Docker (I will), but I've wanted to run it
> on the real hardware for 11 years and I'm one step closer.  I have a
> RK11-D that works, and an RK11-C that will likely require much
> attention (never tried to use it), so the only thing I'm really
> missing (besides enough time to repair/debug all of this) is something
> to emulate an RF11 for the swap disk.  I'm now doubly sad that I lost
> my Diablo 30/RK03 in a flood 25 years ago, but I'll be functional with
> an RK05 or two.
> Fourth - I don't think I got the H720 power supplies with this (or the
> fans) - that was what I think was removed prior to this unit hitting
> the dumpster.  I may have the G772 power cards (and then again, I may
> not), but those wouldn't be hard to reproduce.  I am entirely
> satisfied with modernish switching supplies, but I see the H720 puts
> out about 15A of +5V and -15V, plus -22V for the core and +8V for the
> front panel bulbs.  The bulb voltage is probably no big deal to come
> up with, but -22V is a bit of an oddball.  I'm also willing to forego
> 100% core in favor of MOS memory, including any modern repros that
> come out in the next year or two.  To start, finding even one H720 to
> run the CPU box (I have 2 more boxes for the rest of the memory) would
> be enough to get going.
> So... for now, as I continue to pull the parts together, my real
> question is, what is a KH11-A?
> Thanks for any enlightenment.
> -ethan

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