Magnetic logic is digital logic made using the non-linear properties of wound ferrite cores.[1] Magnetic logic represents 0 and 1 by magnetising cores clockwise or anticlockwise.[2]
Examples of magnetic logic include core memory. Also, AND, OR, NOT and clocked shift logic gates can be constructed using appropriate windings, and the use of diodes.
A complete computer called the ALWAC 800 was constructed using magnetic logic, but it was not commercially successful.The Elliott 803 computer used a combination of magnetic cores (for logic function) and germanium transistors (as pulse amplifiers) for its CPU. It was a commercial success.
William F. Steagall of the Sperry-Rand corporation developed the technology in an effort to improve the reliability of computers. In his patent application,[3] filed in 1954, he stated:
Magnetic logic was able to achieve switching speeds of about 1MHz but was overtaken by semiconductor based electronics which was able to switch much faster.
Solid state semiconductors were able to increase their density according to Moore's Law, and thus proved more effective as IC technology developed.
Magnetic logic has advantages in that it is not volatile, it may be powered down without losing its state.[1]