Magnetic logic is

digital logic A logic gate is an idealized or physical device implementing a Boolean function, a logical operation performed on one or more binary inputs that produces a single binary output. Depending on the context, the term may refer to an ideal logic ga ...

made using the non-linear properties of wound

ferrite core In electronics, a ferrite core is a type of magnetic core made of ferrite on which the windings of electric transformers and other wound components such as inductors are formed. It is used for its properties of high magnetic permeability coup ...

s. Magnetic logic represents 0 and 1 by magnetising cores clockwise or anticlockwise.MAGNETIC CORES - PART I - PROPERTIES - Department of Defense 1962 - PIN 28374 - PROPERTIES OF MAGNETIC CORES AND THEIR APPLICATION IN DATA PROCESSING SYSTEM; HOW INFORMATION IS STORED AND TRANSFERRED FROM ONE CORE TO ANOTHER. Examples of magnetic logic include

core memory Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (manufacturing), used in casting and molding * Core (optical fiber), the signal-carrying portion of an optical fiber * Core, the centr ...

. 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 The Elliott 803 is a small, medium-speed transistor digital computer which was manufactured by the British company Elliott Brothers in the 1960s. About 211 were built. History The 800 series began with the 801, a one-off test machine built in ...

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's application, he states "Where, as here, reliability of operation is a factor of prime importance, vacuum tubes, even though acceptable for most present-day electronic applications, are faced with accuracy requirements of an entirely different order of magnitude. For example, if two devices each having 99.5% reliability response are both utilized in a combined relationship in a given device, that device will have an accuracy or reliability factor of .995 X995 =99%. If ten such devices are combined, the factor drops to 95.1%. If, however, 500 such units are combined, the reliability factor of the device drops to 8.1%, and for a thousand, to 0.67%. It will thus be seen that even though the reliability of operation of individual vacuum tubes may be very much above 99.95%, where many thousands of units are combined, as in the large computers, the reliability factor of each unit must be extremely high to combine to produce an error free device. In practice of course such an ideal can only be approached. Magnetic amplifiers of the type here described meet the necessary requirements of reliability of performance for the combinations discussed." 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.

References

{{reflist Magnetism Logic gates Magnetic logic computers

See also

References