An image forming apparatus includes: an image information input section into which image information is input, and image holding members by which toner images of two or more colors including black and clear colors are held, respectively. In the main cell, a second base layer of the second conductivity type, and an emitter layer of the first conductivity type are disposed. The controller is configured to control the at least two single-phase DCAC converters to deliver power from their inputs to their outputs by turns. The other processing core receives the first hardware signal and stops operation. An arbitrary number of inputs, outputs, neural network node levels, nodes, weighting functions, and thresholding functions for any desired neural network are readily obtained by the methods of the present invention.