Abstract: The apparatus (10) includes a semiconductor tester (12) which in operation produces an analog signature signal relative to a circuit node of an electronic circuit, such as a pin connection of an integrated circuit. The analog signature signal is the result of horizontal and vertical signals which are also directed to an integrator/A-D converter (44) which produces therefrom a set of four digital signals representing said analog signature. These digital signals are then compared in a computer (50) against reference digital values for the same circuit node of the same electronic circuit which is known to be good. If the digital signals are not within a selected range relative to the reference digital values, the analog signature of the circuit node is displayed for inspection and evaluation by an operator.