11/73 into 11/03 chassis?

Noel Chiappa jnc at mercury.lcs.mit.edu
Tue Feb 9 10:27:25 CST 2016

    > From: Jacob Ritorto

    > Can I tear apart my little BA23 .. and put the Micro/PDP-11 backplane
    > .. into the spot that my 11/03 backplane currently occupies and run it
    > via the (working) stock 11/03 power supply?
    > ...
    > Specifically, would I have to butcher power and clock lines to do this,
    > or is it all plug compatible? 

I'm not absolutely sure exactly what you have that's holding the '11/03
backplane'; if it's a standard BA11-M enclosure, the answer, sadly, is 'no'.

The BA-23 uses the H9278-A backplane and H7864 power supply; the BA11-M uses
the H9270-A and H780 backplane. The power connections between the first two
are completely different from the latter pair; the first uses a long,
single-width Molex-type connector, the latter uses bare wire ends to a
terminal block on the backplane.

Also, the H9270-A is a four-slot backplane, and the H9278-A (an eight-slot)
almost certainly will not physically fit into the space for the former.

If your '11/03 backplane' is a different kind of backplane, in some other kind
of box (e.g. BA11-N or BA11-S), the answer, sadly, is still 'no', because they
both also use terminal blocks for power. (Although if you have a BA11-S, you'd
already be set, those are Q22 native.)

Really, it's not that hard to upgrade an H9270-A (or the H9273-A in a BA11-N)
to Q22 (I have done several of the latter); the transplant you speak of (were
it possible) is on the same order of magnitude of work.


PS: In dragging my BA23 out to look at it, it dawned on me that I will
probably never, ever use it - I now have several BA11-N/S boxes, and prefer
them. (I don't need to run the later disks that need the BA23.) So if someone
is interested in the either the BA23, or the spare H7864 I have for it, please
let me know. I'll let either go for my original cost plus shipping.

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