Help with PCB ID

Warner Losh imp at
Sat Mar 13 15:10:11 CST 2021

On Sat, Mar 13, 2021, 1:04 PM Chuck Guzis via cctalk <cctalk at>

> On 3/13/21 11:43 AM, Cory Heisterkamp via cctalk wrote:
> > I’m wondering if anyone recognizes this PCB.  Double-sided, 74xx
> vintage, measuring 14”x15”. There’s a “B.I.” logo in one corner, but no
> google match. IC date codes are ’77/’78 vintage.
> >
> > There’s a pair of DB-25’s, a BCD encoder, and for some reason, two pots.
> DC rectification appears to take place onboard. I thought perhaps the
> 112-7753 marking might be a part or catalog number, however the flip side
> is marked 112-1754, so perhaps not.
> >
> > Anyone recognize it?  -Cory
> >
> >
> Looks like the board from a B100.   Note the connectors and switches on
> rear panel that seem to correspond with this:

It matches my recollection of the day I took the one we had a school...
secretly so the teachers wouldn't get mad...


> --Chuck

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