Memistor

Essentially, a resistor with memory able to perform logic operations and store information, it is a three-terminal implementation of the memristor.

While the memristor is defined in terms of a two-terminal circuit element, there was an implementation of a three-terminal device called a memistor developed by Bernard Widrow in 1960.

Memistors formed basic components of a neural network architecture called ADALINE developed by Widrow.

Reproducible elements have been made which are continuously variable (thousands of possible analog storage levels), and which typically vary in resistance from 100 ohms to 1 ohm, and cover this range in about 10 seconds with several milliamperes of plating current.

However, one of the main limitations of Widrow's memistors was that they were made from an electroplating cell rather than as a solid-state circuit element.