MEM11 Status Update

Noel Chiappa jnc at
Wed Jan 21 11:29:08 CST 2015

    > From: Guy Sotomayor

    > I'm building a "LED" board that attaches to the MEM11. ... I couldn't
    > resist more blinkin lights.

Oh frabjous day! Das blinken-litz!! Excellent!!!

Now I'm _really_ going to want a stack of these... :-)

    > The LED board will display all of the indicators for the RF11
    > controller in a layout similar to what was on a real RF11. ...
    > It's optional and will connect to the MEM11 with a small cable (I plan
    > on using RS485 drivers for the cable) so the LED board can be a fair
    > distance away.

Hmm. Looking at the original RF11 display panel, some of it may be impossible
to really emulate; e.g. it displays the contents of the shift register used
to assemble words from the bit stream being read from the disk; it's probably
not feasible to emulate that... And of course, many of the error bits only
make sense with an actual disk (e.g. the various Timing Track errors).

How much bandwidth will you have from the board to the display panel anyway?
I assume there will be latches on the display panel, and one sends commands
down the link to turn given latches on/off?

Looking at the original display panel, although it had the extended memory
bits, it didn't show the memory address (it does have the disk address).
Maybe we could put that where the shift register display used to be?

(And speaking of the original display, I couldn't find a picture of one - does
someone have one, or, better yet, an actual RF11, so as to copy the look of it
as closely as possible?)

    > (I haven't looked at doing an overlay to make it look pretty)

Oh, yes, please do!!!

    > it'll be somewhat generic (4 rows of 36 LEDs).

I counted up (no doubt you did the same :-), and on the longest row (at the
top), there are 30 lights, plus 4 empty spaces for the gaps between blocks,
so 36 is good. Will you be grouping them in 3's, with slightly larger gaps
between each group of 3? That would really maximize the ability to look just
like the old RF11 display panel.

And warm white LED's, please (of course :-).

I'm really going to have to get going on my UNIBUS PDP-11's. I've mostly been
working on the QBUS ones, but if I can have blinking lights... :-)

I'm already planning on how I can put /, /bin and the pipe device on separate
RF platters, so I can watch the lights and see what the machine is up to.. :-)


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