An electronic instrument that monitors the logic states of digital systems and stores the results for subsequent display. The storage of data is initiated in the analyser by the recognition of preset ‘trigger states’ as these arise in the system under test. Synchronous analysers sample data at intervals determined entirely by the external system. Asynchronous analysers sample at intervals determined internally by the analyser. The essence of a logic analyser is that it copes with many (often 8, 16, or 32) channels in parallel, and that the data recorded can be read back from memory at will, either in binary or after decoding in some way, often by means of a disassembler.