Abstract: A digital storage oscilloscope is capable of responding to its usual assortment of analog trigger signals and is also responsive in real time to an event detection signal provided by a processor unit having an input coupled for receiving a data stream from an A/D converter. The processor unit examines the streaming digital samples of a signal under test in real time for the occurrence of a predetermined event. Upon detection of one of the predetermined events, a frame of data surrounding the event is captured for waveform processing and display. Multiple waveforms can be displayed simultaneously, each being captured in response to a detection of a user-defined anomalous event. A screen display can be programmed to display a different kind of event such as Runt signal, Overshoot, or Pulsewidth Violation in each waveform, or to display multiple occurrences of the same kind of event such as Runt signal in each waveform.