Musical Instrument Digital Interface [MIDI]


(pronounced “MIH-dee”) (n.) An industry-standard hardware/software system for microprocessor control of musical instruments and devices. It defines a protocol for the interchange of musical information between computers, digital musical instruments, and sound boards. MIDI is a simple serial communications bus, like a SCSI bus. The signal is a serial voltage transmission at the rate of 31 250 bits per second (bps). The messages are bytes encoded to define status (the type of message) and data (information about the preceding status byte). The cable is a shielded twisted pair of wires connected to pins 4 and 5 of a five-pin DIN plug. Pin 2 is the ground. Any device with a MIDI port can communicate with another one with similar connections. Only a MIDI interface and software are needed for a computer to control MIDI-compatible digital instruments. The file extension is .mid. See also General MIDI.