IBM 1620

Chuck Guzis cclist at
Sun Aug 30 12:55:53 CDT 2015

On 08/30/2015 09:47 AM, Tothwolf wrote:

> 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.

Wouldn't solderless bonding/welding be a better alternative?

The excuse of "that's too small to work on"  seems a bit 
peculiar-sounding, particularly from people who are used to working by 
hand fine-pitch QFPs with 0.050" lead centers (and smaller).

In the range of core sizes, 1620 cores weren't particularly tiny, 
compared to, say, CDC 7600 SCM core.

So there'd be what, 120,000 cores to thread?  That might be a bit 
daunting from a human-hour standpoint.  I'll wager that 120K cores 
wasn't even a day's output for outfits like Fabritek.


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