Abstract: An interactive diagnostic methodology and apparatus that enables a specimen (microelectronic device) to undergo detailed behavioral examination while allowing the Diagnostician to incrementally proceed from a set of symptoms to a formal diagnosis. Diagnostic tactics are predicated on comparing measured behavior to predicted behavior. The methodology allows coupling to a variety of behavior-level, switch-level (state), and circuit-level (node) simulators in determining predicted behavior. The architecture allows a variety of beam-probing apparatus to be supported in acquiring nodal waveforms and logic state images from a specimen as a means of determining measured behavior. This measured behavior can be graphically compared to the predicted behavior for study and analysis by the Diagnostician to aid in the formulation of diagnostic tactics.