A sequencer that uses digital circuitry to perform all of its functions and to generate all of the information it outputs. Sequencers with digital memory first appeared in the 1970s (the canonical example was the EMS Synti-AKS with its microprocessor-controlled sequencer built into the case lid), and these quickly evolved to be able to store longer and more complex patterns as well as additional performance information. The original designs were usually capable of storing a sequence of notes that was relatively short but still much longer than than what the analog sequencers of the day were capable of, but they were usually strictly "monophonic" in that they could output note data for only note at a time. Methods for synchronizing to external clock sources ware also lacking.
In the 1980s, synth manufacturers began including sequencers in some of their synth designs, and equipping them with MIDI outputs so that one sequencer could easily control multiple devices. Since they were so often used to control drum machines, models started to appear which incorporated both the drum machine and the sequencer in one device. Today, stand-alone digital sequencers are far less common then sequencers built into drum machines or workstation keyboards.