Short answers, pulled from the story.
Al-Jazari unveiled a mechanical marvel in 1206 that became the first programmable drum machine. This robot band featured four automaton musicians and used gears, cams, and levers to perform over fifty distinct actions during a single musical selection.
Roland Corporation released the MC-8 MicroComposer in 1977 as an early stand-alone microprocessor-based digital sequencer. This device boasted 16 kilobytes of RAM and allowed for eight-channel polyphony to create polyrhythmic sequences.
Roland Corporation founder Ikutaro Kakehashi proposed the MIDI standard in June 1981 to standardize communication between different manufacturers. The MIDI standard was officially unveiled in 1983, and the first MIDI sequencer, the Roland MSQ-700, was released that same year.
Software sequencers known as trackers were developed in 1987 to realize the low-cost integration of sampling sound and interactive digital sequencing. These programs allowed users to create music using a grid-based interface where notes were entered as hexadecimal codes.
New England Digital released the Synclavier I in 1977 as one of the earliest digital music workstation products to feature a multitrack sequencer. The Synclavier series evolved through the mid-1980s and established the integration of digital audio and music sequencing.