Programming a music sequencer?

A music sequencer (or simply sequencer) is a device or application software that can record, edit, or play back music, by handling note and performance information in several forms, typically MIDI or CV/Gate, and possibly audio and automation data for DAWs and plug-ins. Also, music sequencer can be categorized by its construction and supporting modes. With the advent of MIDI and particularly Atari ST in 1980s, programmers were able to write software that could record and play back the notes played by a musician.

Unlike the early sequencers used to play mechanical sounding sequence with exactly equal length, the new ones recorded and played back expressive performances by real musicians. These were typically used to control external synthesizers, especially rackmounted sound modules as it was no longer necessary for each synthesizer to have its own keyboard. As the technology matured, sequencers gained more features, and integrated the ability to record multitrack audio.

Sequencers mainly used for audio are often called digital audio workstations (or DAWs). Many modern sequencers can also control virtual instruments implemented as software plug-ins, allowing musicians to replace separate synthesizers with software equivalents. Today the term "sequencer" is often used to describe software.

However, hardware sequencers still exist. Workstation keyboards have their own proprietary built-in MIDI sequencers. Drum machines and some older synthesizers have their own step sequencer built in.

There are still also standalone hardware MIDI sequencers, although the market demand for those has diminished greatly due to the greater feature set of their software counterparts. The early music sequencers had appeared in the form of various automatic musical instruments, including music boxes, mechanical organs, player pianos, Orchestrions, etc. For example, authoring process of piano roll fits the definition of music sequencer: composers record their music composition on the piano rolls, then specialists edit the rolls as the preparation before mass duplication, and finally consumers play back the music on their player pianos. The origin of automatic musical instruments seems considerably old.

As early as 9th century, Persian inventors Ban? M? S?

Brothers invented hydropowered organ using exchangeable cylinders with pins,2 and also automatic flute player using steam power,34 as described on their Book of Ingenious Devices. In 14th century, rotating cylinder with pins were used to play carillon in Flanders,citation needed and at least in 15th century, barrel organs were seen in the Netherlands. In 19th century, as the results of Industrial Revolution, various automatic musical instruments were invented, for examples: music box, barrel organ and barrel piano using barrel / cylinder with pins or metal disc with punched holes; or mechanical organ, player piano and orchestrion using book music / music rolls (piano rolls) with punched holes, etc. These instruments were widely spread as the popular entertainment devices before the inventions of phonograph, radio, and sound film.

Amongst of all, especially the punched tape media had been long lived until mid-20th century: earliest programmable music synthesizers including RCA Mark II Sound Synthesizer in 1957, and Siemens Synthesizer in 1959, were also controlled via punch tapes similar to piano rolls. Another inventions were came from sound film technology. The drawn sound technique which appeared in the late 1920s, is notable as a precursor of today's intuitive graphical user interfaces.

On this technique, notes and various sound parameters were controlled by hand-drawn waves on the films, resembling piano rolls or strip charts on the modern sequencers/DAWs. During 1940s–1960s, Raymond Scott, an American composer of electronic music have invented various kind of music sequencers for his electric compositions. The "Wall of Sound", once covered on the wall of his studio in New York during 1940s–1950s, was a electro-mechanical sequencer to produce rhythmic patterns, consisting with stepping relays (used on dial pulse telephone exchange), solenoids, control switches, and tone circuits with 16 individual oscillators.

9 Later, Robert Moog explained it “the whole room would go 'clack - clack - clack', and the sounds would come out all over the place”. 10 The Circle Machine, developed in 1959, had dimmer bulbs arranged in a ring, and a rotating arm with photocell scanning over the ring, to generate arbitrary waveform.