Repairing core memories....
ard at p850ug1.demon.co.uk
Sun Oct 31 13:28:15 CDT 2010
> So I have these 2 PDP-8/L core stacks I am trying to recover:
> One would be perfect, if bit 3 @ adr 0 would be alive...
> Although this is 99.99% OK, it is of course not good enough.
> The other stack seems to be a total loss :
> 2 sense wires are open circuit, more than 20 select diodes shorted.
> Of course the further quality of the cores is unknown.
> Is there any realistic way of getting one fully functional stack out
> of these ?
> Removing a single core from the really bad stack to the almost OK
> stack would seems almost feasible to me, since address 0 is bound to be
>L on a edge of a core mat.
Its likely to be, I guess, but I wouldn't bet much on the physuical
layout of the core plane. In any case the sense and inhibit lines are
going to run through a lot of cores, so you'll have to remove and replace
those I think.
I have never tried to repari core memory (otehr than the drive
electronics), and I believe that fore some later core memoryies, the cors
were cast around the wiees after the wires had been laid out, so you
can't untrhead and retrhead that type. But older ones were made by
threading wires trhoug hthe cores, so it may be possible.
What I would do is practice on the totally dead plane. See if you can
remove the wires, take a core out, and then thread the wires back again.
When you get good at doing that, then have a go at fixing the almost-good
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