1. Apparatus for diagnosing abnormal behavior in a mal-functioning integrated circuit specimen comprising in combination: noncontact probe means for acquiring voltage waveforms to be measured at selectible circuit nodes within the specimen; stimulator means; simulator means computer means including display means for composing, modifying and displaying input stimuli patterns for application to the stimulator means the simulator means; said stimulator means utilizing said input stimuli patterns from the computer means for dynamically exercising the specimen to output voltage waveforms to be measured; said simulator means storing a mathematical model of the integrated circuit specimen, as designed, in the form of object clustering data structure enabling concurrent production of corresponding predicted waveforms and waveforms to be measured due to simultaneous stimulation of the specimen and the simulator means; said display means further exhibiting pictorial representation of the specimen layout, as described in the mathematical model, to allow an operator select a node on the layout where comparison of measured and simulated waveforms from the mathematical node and corresponding specimen node are to be made; said simulator means outputting predicted behavioral characteristics of the circuit specimen as predicted waveforms applied to the display means along with any output waveform of the noncontact probe means acquired during said exercising; and said display means also enabling pictorial comparison of said predicted and measured waveforms to permit identification of circuit errors causing abnormal behavior in the specimen.