A Straightforward Way of Generating All Boolean Functions of N Variables Using a Single Magnetic Circuit

A correspondence has been established1 between the topology of relay contact networks and the topology of magnetic circuits, which may be applied to a relay tree to produce a magnetic structure capable of generating, in a simple manner, all Boolean functions of N variables. Once the basic magnetic topology is established, it may be distorted to achieve winding simplicity at the expense of magnetic circuit complexity. In the resulting arrangement, the drive, hold (variable) and reset windings are always in the same position, regardless of the function to be generated. Any one of the 22N functions of N variables is generated by linking a selected group of the output legs. The structure is such that all switching paths are of equal length, causing all outputs to be equal in amplitude. This balanced arrangement also permits the holding MMF to be significantly smaller than the drive MMF. The holding scheme is a symmetrical one, specifically arranged to overcome shuttle flux problems and reduce noise. An 8-leg manganese magnesium zinc ferrite structure is operated easily at a 4-¿sec cycle time with an output of 500 mv into 5 ohms. The peak-signal-to-peak noise ratio was at worst 8:1. A 1-in-256 selector, using seventeen 16-leg structures, is under constuction. The structure described here is in a sense the complement of the laddic,2 in that the drive and hold windings are always applied in fixed positions and different functions are generated by linking different sets of output legs.