RK11-C indicator panel inlays?

Jay Jaeger cube1 at charter.net
Tue Dec 7 10:11:28 CST 2021

I would be interested in an inlay - I have an RK11-C, but no indicator 

Also, if someone (else, presumably) does up a replica of the indicator 
panel board (perhaps with the option to use LEDs, with some resistor 
packs that could be bypassed for lamps), I'd be interested in that, too.

As a BTW, when I got my PDP-11/20 from the U Wisc. ECE dept. they had a 
home grown 11.5" high indicator panel that watched the bus signals and 
displayed the registers and PSW in LED's.  I disconnected it, but I 
think I left the connector in place on the 11/20 for it.


On 12/5/2021 1:12 PM, Noel Chiappa via cctalk wrote:
> Let me get this out before the list gets shut down _again_...
> There is discussion of doing a run of indicator panel inlays:
>    http://ana-3.lcs.mit.edu/~jnc/tech/DECIndicatorPanels.html
> for the RK11-C (which is wired for an indicator panel, although as far as
> I know, DEC never did the inlay).
> If you're interested... you will need a standard DEC indicator panel light
> panel (with flat cables with plug-in-cards on the ends). (I don't have any
> insight on how to get one of those. It shouldn't be _too_ hard to make
> replicas, but I'll leave that topic for the moment.)
> All I am proposing to do is create the silk-screened inlay that turns a DEC
> indicator panel into an RK11-C indicator panel (starting with a functional
> indicator penel without the inlay).
> All DEC indicator panels use the same actual light panel and flat
> cables/plug-in-cards (which have one conductor per light in the light panel);
> which light comes on is set by the way the backplane slots the
> cables/plug-in-cards plug into are wired.
> So from the prints, which give the wiring to the indicator panel slots, I
> managed to work out what an RK11-C panel would look like, roughly (captions
> are made up, but the light locations are accurate):
>    http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/RK11-C_inlay.txt
> Starting with that, Dave Bridgham managed to whip up a rough approcimation of
> what the inlay would look like:
>    http://pdp10.froghouse.org/qsic/inlay-rk11-c.pdf
> We had put a certain amount of work into identifying a font which looks like
> the one DEC used, back when; I worked with a member the UK to produce a bunch
> of blank inlays (right size/shape, with the black paint on the back with the
> holes for the lights). Dave then found someone who could print the white
> lettering on the front, and this is what the result looked like, on an
> 'RK11-F' (the QSIC with RK emulation microcode) panel:
>    http://ana-3.lcs.mit.edu/~jnc/tech/QSIC/jpg/RK11F-F.jpg
> You can compare with an original DEC inlay (TC08, IIRC) here:
>    http://ana-3.lcs.mit.edu/~jnc/tech/QSIC/jpg/DasBlinken2F.jpg
> That's on the same light panel, just the inlay is changed. (The lights in the
> lower one are from the light panel Dave produced for use with the QSIC; it's
> totally incompatible, electrically, with the DEC originals; 4 wires, IIRC, run
> the whole thing (data, clock, latch and a ground), as opposed to the 'wire per
> light' of the DEC originals. Looks _just_ like the originals (which Tech Sq
> used to have a lot of, BITD), though.
> Anyway, if anyone is interested, the next step would be to find out who all
> wants an RK11-C inlay, and work out _exactly_ what would be printed on it.
> 	Noel

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