40k Ferrite Memory Core

Pete Turnbull pete at dunnington.plus.com
Wed Oct 29 18:25:03 CDT 2008

On 29/10/2008 19:52, Rick Bensene wrote:

> I agree with Brent's analysis.  I too counted 21 planes, which seems a
> bit odd, as typically each plane represented one bit in a word
> structure, which would indicate a 21-bit word...not something that
> matches up with commonly-used word sizes in 50's/60's era computers (12,
> 16, 18, 20, 24, 32, 36, 48, 60 or 64 bits).

It looks pretty intact, and I don't think anything's been stripped. 
However, while I count 21 layers (image 2 and image 4) in the 
construction, the top layer has no cores (plain to see in images 3 and 
4), so there are 20 planes by my reckoning.

And counting rows and columns of cores (not just the wires), I see 40 x 
50 (you can easily count them in image 4), which matches the X and Y 
numbering on the connectors.  So I still reckon that stack is 2000 words 
x 20 bits.

Pete						Peter Turnbull
						Network Manager
						University of York

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