Patent US 4,091,359

The present invention relates to a modular logic circuit, which is preferably utilized in a telephone switching system, comprising electronic logic elements using binary logic operation. The input terminals of the circuit have one input signal at a time applied to them whereupon an output signal is supplied through its output terminals; the output is dependent on how the modular circuit was previously set by electrical means. The logic elements comprise transistors in a matrix arrangement connected to horizontal and vertical lines. The modular circuit of the present invention is characterized in that it can be set any number of times by means of a first setting signal applied to the input terminals and a second setting signal applied simultaneously to the output terminals. The setting signal applied to the input terminals is fed to specified horizontal lines, while the setting signal applied to the output terminals affects at least one vertical line by way of selector switches that connect the output signal path to the output terminals.