PhiLiZound Software
Page updated: 3-Feb-2012

Sequetron History

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The idea was conceived in the late 1980s to address problems creating simple musical accompaniments & backing tracks using conventional computer sequencers. Several commercial products were tried, with a wide range of playback & editing features, but all seemed unnecessarily cumbersome when recording. This was compounded by having to repeatedly switch between music keyboard and computer keyboard/mouse, all of which stifled musical spontaneity & creativity.

The solution was to design a control language based solely on MIDI notes, which would allow the ''same'' instrument to be used for both play & control, then implementing an interpreter for this language. The first proof-of-concept interpreter was a Turbo Pascal program running under MS-DOS on an 80386 PC. The MIDI interface was an MPU-401 card running in normal/intelligent mode, which was a standard method of achieving good response times from the low-performance PCs of that era. The card provided MIDI time-stamping and 8 playback tracks, which dictated the original design layout of 7 tracks plus one 'live' track. In practice the limiting factor on numbers of tracks was more to do with how much status information the musician could hold mentally as there was no display device, and this layout has remained the default factory setting through to the current implementation even though many more tracks can now be handled.

It was to be marketed as a turn-key system (called 'The Sequetron') which would include the PC base unit preloaded with software, with no screen, keyboard or mouse. The only connections to the outside world were power and MIDI in/out sockets. The user would be able to plug their MIDI keyboard and MIDI synthesiser/sound device into the Sequetron (which could then be placed out of sight) and control everything from the MIDI keyboard. An optional display device for basic status feedback was later planned but never built, comprising a strip of LED lights laid over the user's music keyboard and driven by the PC's printer port.

In the early 1990s the program was rewritten in 80386 assembler code to handle extended memory and fix interrupt problems between the MIDI card and Pascal. This was the first fully working prototype, but remained with the author as a practical studio instrument while more development took place.

There was still no musical need for a display screen (program debugging/tracing used morse code via the internal PC 'beep' speaker), but as the program grew in functionality it was harder to play and keep track mentally, so the PC screen was finally utilised and the LED lights idea was scrapped. Plans for including any other hardware were then scrapped on cost grounds and it became a software-only project.

Mk-I screenshot
Original Mk-I character-based status display; only the last line changed,
everything else was static help information

Mk-I screenshot + keyboard
Mk-I run-time status line showing keyboard mode &
sequences 1-6 with seq 7 used as metronome

In 2007, this Mk-I program was published along with a YouTube video demo.



The scarcity of DOS-based PCs and MPU-401 intelligent cards (now obsolete due to the increase in native PC power) meant the Mk-I program was no longer usable by others, so it was rewritten in Delphi Pascal for running on PCs with any supported MIDI devices, including those connected via USB.
Mk-II screenshot
Mk-II main status window showing 4 sequences/tracks

Mk-II screenshot + virtual keyboard
Mk-II main status & optional dynamic template/virtual keyboard window

In April 2010, this first Mk-II program was released.

The use of a high level language made it easier to develop new features, such as saving/loading MIDI files, external synchronisation etc., but although these have advanced considerably, the underlying Mk-I command sequence syntax has remained unchanged.