IBM 1620

Tothwolf tothwolf at concentric.net
Sun Aug 30 11:47:33 CDT 2015


On Sun, 30 Aug 2015, Dave G4UGM wrote:
> On Sat, 29 Aug 2015, Tothwolf wrote:
>
>> IBM had special machines to position and thread them. 
>> http://ibm-1401.info/IBMCoreArraysIEEEMagnetics1969.pdf
>
> Thanks for posting that. Very interesting. Looking at it, the machines are
> extremely complex, but I am sure they could be reproduced, albeit at a
> probably prohibitive cost...
> .. I have marked for later reading...

Something else I forgot to mention, is that on page 8 in that pdf file, 
they mention initially using 60/40 tin-lead alloy solder for the enamel 
wire to the core plane terminals. On page 9, they describe switching to 
20/80 tin-lead so the solder would dissolve less copper from the enamel 
wire.

If repair of the core memory in CHM's IBM 1620 is ever attempted, I think 
either low-tin solder alloy with 1-2% added copper or possibly a more 
modern indium-lead solder alloy would probably be the best choice for the 
enamel wire to terminal connections since that would greatly reduce the 
likelihood of any future wire breakage.


More information about the cctalk mailing list