Plated wire memory

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Plated wire memory is a variation of core memory developed by Bell Laboratories in 1957. Its primary advantage was that it could be machine-assembled, which potentially led to lower prices than the hand-assembled core.

Instead of threading individual ferrite cores on wires, plated wire memory used a grid of wires coated with a thin layer of iron-nickel alloy (called permalloy). The magnetic field normally stored in the ferrite core was instead stored on the wire itself. Operation was generally similar to core memory, with the wire itself acting as the data line and the magnetic domains providing the individual bit locations defined by address (word) lines running on either side of (and perpendicular to) the data wire.

Early versions operated in a destructive read mode requiring a write after read to restore data. Non-destructive read mode was possible but this required much great uniformity of the magnetic coating.

Increasingly high density semiconductor memories such as the 1K Dynamic RAM provided the higher storage densities and higher speeds needed for large scale application such as mainframe computers.

Plated wire memory has been used in a number of applications, typically in aerospace. It was used in the UNIVAC 1110 and UNIVAC 9000 series computers, the Viking program that sent landers to Mars, the Voyager space probes, a prototype guidance computer for the Minuteman-III, the Space Shuttle Main Engine Controllers, [1] KH-9 Hexagon reconnaissance satellite [2] and in the Hubble Space Telescope.

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References

  1. Tomayko, James. "Chapter Four: Computers in the Space Shuttle Avionics System". Computers in Spaceflight: The NASA Experience. NASA. Retrieved 8 August 2011.
  2. "The HEXAGON story". National Reconnaissance Office. 1988.