On Sun, Aug 21, 2016 at 1:53 PM, Noel Chiappa <jnc at mercury.lcs.mit.edu> wrote: 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