Hardware Detail

Item Reference:	HW0322
Machine Type:	604 Core Storage	Serial Number:
	Ferrite core memory / control matrix for the IBM 604
	This is an early example of ferrite core storage used in the IBM 604. Copper wires are threaded through the ferrite cores horizontally and vertically, allowing each core to be addressed via on vertical (X axis) and one horizontal (Y axis) wire. The ferrite cores are magnetized in one direction or the other, to represent a 1 or a 0. By sending half the current needed to reverse the polarity down each wire, only the core where the wires cross is affected. A third wire is looped through all cores, and is used to sense the polarity of a core when addressed by the X and Y wires. A technique called 'destructive read' is used. The circuitry attempts to flip the core (bit) being addressed to its zero state. If already zero, the core is not flipped, if it was 1 then it is, producing a voltage pulse in the sense line. If a 1 is required, it has to be rewritten immediately.
Date of Origin:	1958	Donor:
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Location:	On Display - HLG46	Commissioned By:	Until: