-----Original Message----- > From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Tothwolf > Sent: Sunday, August 30, 2015 1:57 AM > To: General Discussion: On-Topic and Off-Topic Posts > <cctalk@classiccmp.org> > Subject: Re: IBM 1620 > > On Sat, 29 Aug 2015, Paul Koning wrote: > > On Aug 29, 2015, at 12:36 AM, Lyle Bickley <lbick...@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. > > Those particular cores are quite small and I'm not sure a 3d printer would be > 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
