Preliminary core memory technology page.

Oh no, not another computer museum!

Detail from a core memory board. Originally from a CompuData bookkeeping machine.
Not this CompuData, nor this CompuData, nor this CompuData, nor this CompuData, nor this CompuData, nor this CompuData, nor this CompuData, nor this CompuData, nor this CompuData, nor this CompuData, nor this CompuData, nor ...

The board from which the picture above is a detail, has four linked mats of 20 x 53 cores (=bits). So this leads to a grand total of 4240 bits.

The whole board.

This board has four wires through each core. Per mat there are two black wires. These are probably the sense/inhibit wires. But from this info, and from the links below, I cannot determine how many bits can be addressed simultaneously per mat/board. Probably more than one, which is the limit on basic three wire mats.

R. Tim Coslet solved the problem for me:

It looks to me like a 4 bit wide memory, with probably 1040 addresses.

Each of the 4 "planes" is 20 by ~52.

There are 4 wires through each plane, probably "x", "y", "inhibit", and "sense".

So this board is more than one 'kilo-nibble', half a kilo-byte.

Generic links:

• Core memory shield for the Arduino. I wanted to make something like this for ages to demonstrate the magnetic core properties, but these guys actually did it!
• Core Memory Great information on the operation of core memory.
• Museum of Hewlett Packard calculators including core ROM. This schematic looks a bit like my board.
• More info on core memory
• Article EDN, June 1996 Core memory memories.
• Over de werking van Ringkerngeheugens (Dutch)
• Look at Wouter'a Classic Computer Collection page for a scan of a very informative article from Byte magazine from 1976.

Last updated: 2011-05-13

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