30 Aug
2015
30 Aug
'15
1:49 a.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org]
On Behalf Of Tothwolf
Sent: Sunday, August 30, 2015 1:57 AM
To: General Discussion: On-Topic and Off-Topic Posts
<cctalk at classiccmp.org>
Subject: Re: IBM 1620
On Sat, 29 Aug 2015, Paul Koning wrote:
Those particular cores are quite small and I'm not sure a 3d printer would
be
On Aug 29, 2015, at 12:36 AM, Lyle Bickley
<lbickley at bickleywest.com>
wrote:
> I was not on the Team that did the memory analysis and the ultimate
> "modern" replacement memory. However, when I joined the Team, I
asked
similar
questions and was told that the core memory was literally
"falling apart" and was not repairable.
I sure have a hard time fathoming any of this.
Quite apart from the obvious one of building a pin-compatible modern
memory, another answer comes to mind. If a core plane has come apart,
the cores could be recovered and restrung. That requires patience and
dexterity, but it should be doable. It also requires a device to hold
the cores correctly for threading; something like that could easily be
made in a a 3d printer. able to print a jig with the tolerances required.
Perhaps a consumer 3-D printer wouldn't, but there are higher precision
printers out there that will print to a high accuracy.
Also not that 3-D printing with filament is just a small part of a wide
range of techniques available. There are several processes:-
http://3dprintingindustry.com/3d-printing-basics-free-beginners-guide/proces
ses/
some of which are not available to the Amateur because of cost (especially
un-expired patents) or just too complex...
There are also subtractive manufacturing methods such as laser
cutting/etching and CNC milling which could be more suitable for building a
core jig....
.. Most of the FabLabs will have one of these available
http://www.rolanddg.com/product/3d/3d/mdx-20_15/application.html
and a laser cutter....
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...
I can certainly understand why repair wasn't
initially attempted, however
that doesn't mean it is impossible. Given the rarity of the system,
welding
new stubs of wire to the original enamel wire or
completely rebuilding the
core planes with all new wire might still well be a worthwhile project at
some
point in the future. It might even be possible to keep
most of the cores
in
position and rethread just one portion (X, Y,
sense/inhibit) at a time.
Another plus is that because of the way the wires are threaded, it is
unlikely
that any of the cores have been lost, even if a large
number of wires have
broken at the terminals.
Dave Wade
G4UGM