Logic analyzer

A logic analyzer is a piece of electronic test equipment, used for observing the waveforms of incoming digital signals as a function of time. It allows the observer to see the waveforms present in the circuit as it operates; it is also used for debugging equipment which has developed a fault.

A logic analyzer consists of a number of fairly large shift registers; while it is in 'record' mode, the sense of each monitored signal is inserted into the end of the associated shift register at every clock time. When it is 'triggered' - i.e. told to freeze its record of the sense of all the monitored signals prior to the triggering event - it ceases to insert new data, and switches to a mode where it displays the previously-recorded data.

The first generations used a CRT to display the data; more recent ones use an LED or LCD screen.