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- Magnetic logic is digital logic made using the non-linear properties of wound ferrite cores. Magnetic logic represents 0 and 1 by magnetising cores clockwise or anticlockwise. 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'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. (en)
- 磁性体論理素子(英名:Magnetic logic) はフェライトコアの非線形特性を利用した、磁性体を利用した電子回路で構成される論理回路である。ドーナツ型の磁性体コアの、磁化が時計回りか反時計回りか、によって0と1を表す。 AND、OR、NOTとクロックシフト論理ゲートなどが、適切な配線とダイオードの併用により構築可能である。採用機として、「ALWAC 800」は完成したが、商業的には成功しなかった。「」は（論理機能用）磁気コアと（増幅用）ゲルマニウムトランジスタをプロセッサに使用しており、商業的に成功した。 磁性体論理素子のスイッチ速度はおよそ1MHzに到達できたが、遥かに高速なスイッチ速度の半導体製の電子回路に追い越された。 磁性体論理素子の利点は不揮発性であることで、電源を遮断しても状態を失わない。磁気コアメモリはコンピュータ史上このタイプの論理素子が最も多用された形態で、20年以上使用された (ja)
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