Repairing core memories....

[Tony Duell]

> 
> 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 
one

-tony