[GreenKeys] [External] Re: More BRPE progress: a schematic

[Eric Moore]

Well I have shipped this thing to MIT to support their whirlwind efforts,
and taken it to a couple VCFs. Happy to send it to any universities or VCF
attendees looking to display it running at their booth.

-Eric

On Fri, Apr 18, 2025, 2:46 PM Jones, Douglas W <douglas-w-jones at uiowa.edu>
wrote:

> From: Eric Moore <mooreericnyc at gmail.com> -- Friday, April 18, 2025 2:21
> PM
>
> > Hey Doug, my fully operational 8 bit BRPE and encoder is packed in a
> pelican case and ready to ship if it would be useful to you.
>
> I'm a long way from needing a working BRPE.  We've got a 1965-vintage PDP8
> that will eventually be able to drive the BRPE, but before that, we need to
> get the core memory working.  It hasn't worked at all until last Monday,
> when we got the first nonzero values out of memory that I've ever seen.
>
> Once we get the core tuned up (we have the memory tuning instructions),
> the next order of business will be to toggle in simple programs from the
> front panel to see if the CPU basically works (we know a lot works because
> most of the data paths in the CPU are used when you toggle data into memory
> and then inspect it.
>
> Once we get some simple programs running (like counting in binary), then
> we'll start trying to drive an ASR-33 at 110 baud, and only after we get
> that working will it be time to start working on the (significantly
> trashed) I/O option backplane that includes the paper-tape reader and punch
> controllers.  Only at that point will a working BRPE matter (we also have a
> Tally high-speed paper-tape reader).
>
> Where the BRPE punch seems to be all about buckling knee-joint toggle
> linkages, the Tally Reader is all about differentials.  It has three of
> them, one driving each tape reel and one to drive the tape-advance sprocket
> wheel.  I photographed one of the Tally differentials to illustrate the
> Wikipedia page on differentials.
>
>            Doug Jones
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