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Thin film memory
From Wikipedia, the free encyclopedia
Thin film memory is a high-speed variation of core memory developed by Sperry Rand in a government-funded research project.
Instead of threading individual ferrite cores on wires, a thin film (4 millionths of an inch thick) of iron-nickel alloy (called permalloy) was deposited as small dots (using a mask) on small glass plates by vacuum evaporation techniques. The drive and sense lines were then added using printed circuit wiring over the alloy dots. This provided very fast access times in the range of 670 nanoseconds, but was very expensive to produce.
In 1962, the UNIVAC 1107, intended for the civilian marketplace, used thin film memory only for its 128-word general register stack. Military computers, where money was less of a concern, used larger amounts of thin film memory. Thin-film was also used in a number of high-speed computer projects, including the high-end of the IBM System/360 line, but general advances in core tended to keep pace.