Chapter Three: MIDI

1. MIDI Overview and History

MIDI is the acronym for Musical Instrument Digital Interface. MIDI is a system very much like a player piano roll in that it is used to specify or control the actions of a synthesizer, virtual instrument or other electronic and software devices, while the tone or effect is generated by the instrument or software itself. In other words, MIDI does not produce sound on its own.

The development of the MIDI system was a major catalyst in the explosion of music technology in the late twentieth century. MIDI put powerful computer instrument networks and software in the hands of less technically versed musicians and amateurs and provided new and time-saving tools for computer musicians. The idea goes back to 1981, when Dave Smith and Chet Wood of Sequential Circuits proposed a "Universal Synthesizer Interface" to the Audio Engineering Society. The system took shape in 1982 following an agreement among manufacturers and developers of electronic musical instruments to include a common set of hardware connectors and digital codes in their instrument design. It was first shown publicly at the January 1983 trade show of the National Association of Music Merchants (NAMM), where a Sequential Prophet-600 and a Roland Jupiter-6 were linked by MIDI. Later that year the International MIDI Association (IMA) formally released the MIDI 1.0 Specification. According to Joel Chadabe in Electric Sound (1997), the IMA was formed to disseminate information, while a separate MIDI Manufacturers Association handled technical issues. Roland, Yamaha, Korg, Kawai and Sequential Circuits all came out with MIDI-capable instruments in 1983.

Yet more than 40 years on, MIDI is still in common use, working with advanced synthesis software like Max and SuperCollider, theatrical lighting systems and show control, fireworks and Christmas light show synchronization, and a host of other applications not dreamed of when it was first proposed.

The original goal was to connect or interface instruments of different manufacture to control common functions, such as note events, timing events, pitch bends and pedal information. A note played, a patch changed or a pedal pressed on one instrument would have the same effect on another connected via MIDI cables, even if it was of a different brand. As small, affordable computers, such as the Apple II, became available, it wasn't long before instruments were hooked up through a MIDI interface to the computer as well as to each other. This allowed programmers to write MIDI sequencing and editor/librarian software (programs for editing and storing a synthesizer's sounds, or patches). The Atari ST, introduced in 1985, went a step further with MIDI ports built in, and it quickly became a favorite platform for that software.

Though several classes of codes have been added to the MIDI 1.0 Specification (International MIDI Association, 1989) and MIDI applications have grown far beyond the original intent, the basic protocol in use today has remained relatively unchanged. In 2020, however, MIDI 2.0, the first major update in nearly 40 years, was released. Support came slowly at first, but every major computer operating system now handles it, and a growing number of instruments and programs use it. It was designed to be backward compatible with MIDI 1.0 devices and software. MIDI 2.0 uses two-way communication to determine the functionality of a device, auto-configure devices to work together, or recognize that a device is only MIDI 1.0-capable and communicate on that level alone.

For comprehensive, up-to-date information, including additions to the specification and topics beyond the scope of this chapter, an excellent online source is MIDI.org. A free registration provides access to many MIDI Manufacturers Association documents, including the MIDI 2.0 specification itself.