[rescue] DG Nova "pico end" backplane device

Skeezics Boondoggle skeezicsb at gmail.com
Sun Apr 22 21:37:41 CDT 2018


Hey, guys --

This might be a little obscure, even for this list. :-)

Way back in the day I worked on DG Nova clones, running the BITS operating
system.  There was a thriving little niche in the '80s for IDP, Bytronix,
Point4, Star Technologies, and others, nearly all of whom are utterly
forgotten these days... BITS was a business BASIC environment similar to
IRIS from Point4.  It was licensed using a hardware device they called a
"pico end" that slipped over the wire-wrap pins protruding from the
backplane.  It was little more than a lump of epoxy concealing a PROM that
provided a hardware license key.  One company made a small cache memory
board that was attached in the same way, so that it didn't occupy an entire
slot in the card cage.  Naturally I have had absolutely zero luck finding
any references to this online.

I'm fishing for suggestions for creating a similar mounting for an extender
board for doing hardware debugging.  The idea is to create a long thin PCB
with two rows of sockets that slip over the wire-wrap pins on the
backplane, and two female card-edge connectors on the other side to mount
the card under test.  To build a traditional extender board is
prohibitively expensive (12" x 15") and the margin for clock skew is only
1.5ns anyway... hanging the board off the backplane directly (with
appropriate mechanical support) would keep trace lengths as short as
possible and massively reduce the cost of producing the thing.

Anyone have any suggestions for sockets to fit over .510" wire wrap pins?
It's two columns of 100 pins each, with .1" row spacing.  It doesn't look
like any of the typical IC sockets or female pin headers have enough depth
even when fully seated for a secure mount.  Just curious if any of you have
or have heard of a similar strategy for something like this?

Thanks,

-- Chris


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