How scarce (valuable) is core for the PDP-8?

From: Allison J Parent <allisonp_at_world.std.com>
Date: Mon Apr 19 18:28:23 1999

<sort of a "one from column A, two from column B" approach. As long as the
<sense amps don't balk at the extra resistance of doubling the length of
<of the sense wire, it could work.

Not likely but ther eis anotehr totally different problem, asymetric noise
pickup masking the cores switching. Your further ahead fixing the mat.
The wire used should present little trouble as fine wire can still be had.

As an aside to this with the lamers trophying the mats. Most often the
mats are intact so someday they could again be spares. The best one I've
ever seen was not real but instead used small nuts and three colors of
wire to make a real looking mat of some 64 or 128 bits. I'd bet that
with the right currents and timing you could even store data in it.

Also anyone holding a "core" based machine knows enough to keep spares
as that is expensive to fix when your precious machine tool is dead.
Down time for those people costs more than the computer that runs it.

I say this as I have two Qbus PDP11 core sets both known good. Trophy
never. Maybe one day I'll power them up again.


Allison
Received on Mon Apr 19 1999 - 18:28:23 BST