40k Ferrite Memory Core

Brent Hilpert hilpert at cs.ubc.ca
Wed Oct 29 14:55:01 CDT 2008

Pete Turnbull wrote:
> On 29/10/2008 05:23, jim s wrote:
> > I counted 52 wires x 52 wires in the top plane
> > I counted either 20 or 19 total planes
> I count 50 x 40, and 20 planes.  I think you need glasses, Jim :-)
> > In looking at the photo, it appears that there are 2 of those wires thru
> > each core, so this is 26*26*20 or 13520 bits total
> I only see one X and one Y plus the sense wire through each core (and
> the cores are laid out like that), so I make it 2000 x 20 = 40000.
> > The connector marked X has 40 conductors.  I would assume there is also
> > a Y connector, and maybe fewer sense lines?
> 5.jpg shows 50 Y connections.
> > maybe only 1 sense line per plane?
> That's normal.

My read on this is it's a (X=40)*(Y=48) matrix, going by the number of pins on
the X&Y connectors, with 21 planes. I count 52 pins on the Y-side of each plane
of the actual matrix. This makes sense as the extra 4 pins (52-48) would be 2
for the sense line and 2 for the inhibit line of each plane. (The sense and
inhibit connections do not come out to the connectors, there would have been
additional wires connecting down the stack when installed). In
http://www.thegolfballshop.com/oct28/3.jpg, one can see there are 4 wires
through each core: X, Y, sense (diagonal), and inhibit (parallel to X), making
it a pure 3D, 4-wire construction (the loopbacks for the inhibit lines are also

Given other aspects of it's construction (in part, the diagonal sense line) I
think a 3-wire setup would be have been problematic or impossible.

It does give the impression of being 50's-era construction, probably from a
tube machine.

Very pretty, I hope it doesn't get broken up, as intact 3D-stacks like that are
pretty rare these days.

More information about the cctech mailing list