System for digitizing transient signals with waveform accumulator

An apparatus for capturing and digitizing a signal derived from an event has a memory for storing a sequence of analog samples from the signal derived from the event in a sampling operation occurring at about a 0.5 gigahertz or higher sampling rate. Circuitry communicating with the memory selectively initiates the read out of the analog samples in the memories. An array of analog to digital converters receives a sequence of analog samples read out from the memory and produces from the analog samples a corresponding vector of digitized sample values. A waveform accumulator integrated with the array of analog to digital converters receives a vector of digitized sample values from a new waveform and combines these with a vector of digitized sample values from at least one prior waveform. An output stage outputs the vector of digitized sample values developed in the waveform accumulator.