Abstract: A k-fault tolerant AND gate circuit comprises k+1 levels and the input level comprises k+1 AND gates. Embodiments provide intermediate levels arranged for providing a two-fault tolerant AND gate circuit and a four-fault tolerant AND gate circuit, respectively.

Abstract: Feed forward neural network models for associative content addressable memory utilize a first level matrix of resistor connections to store words and compare addressing cues with the stored words represented by connections of unit resistive value, and a winner-take-all circuit for producing a unary output signal corresponding to the word most closely matched in the first matrix. The unary output signal is converted to a binary output code, such as by a suitable matrix. Cues are coded for the address input as binary 1=+V, binary 0=-V, and unknown =0V. Two input amplifiers are employed with two input conductors for each input bit position, one noninverting and the other inverting, so that the winner-take-all circuit at the output of the first matrix may be organized to select the highest number of matches with stored words as the unary output signal.