GENERAL MIDI

This article is about the Synthesizer Specification. For the British DJ, see General Midi (DJ) General MIDI or GM is a specification for synthesizers which imposes several requirements beyond the more abstract MIDI standard. While MIDI itself provides a protocol which ensures that different instruments can interoperate at a fundamental level (e.g. that pressing keys on a MIDI keyboard will cause an attached MIDI sound module to play musical notes), General MIDI (or GM) goes further in two ways: it requires that all GM-compatible instruments meet a certain minimal set of features, such as being able to play at least 24 notes simultaneously (polyphony), and it attaches certain interpretations to many parameters and control messages which were left unspecified in MIDI, such as defining instrument sounds for each of 128 program numbers.
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