30 Aug
2015
30 Aug
'15
11:15 a.m.
On Aug 30, 2015, at 1:55 PM, Chuck Guzis <cclist at
sydex.com> wrote:
On 08/30/2015 09:47 AM, Tothwolf wrote:
That's what the IBM IEEE article mentions.
I'm still a bit puzzled by the dissolving of copper wire by conventional solder. The
wire used in core memories is thin, but not outrageously so by the standards of, say, Litz
wire, and that is soldered routinely.
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? ...
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.
Those cores weren't threaded one by one. You'd start by setting the cores into a
holding jig, which positions them correctly. Then you thread wire from edge to edge. The
article mentions a needle with the wire welded to its end; that makes sense because the
copper wire is unlikely to be stiff enough. So the number of individual threading
operations is 3-4x the square root of the core plane size. For example, on a 4k core
plane, it would be 200 steps, give or take. (A bit more on a CDC 6000 series core plane
with its peculiar 5 wire architecture.)
paul