MIDI messages can be broken into two constituent parts: data bytes and status bytes. The status byte is the portion of a MIDI message that defines the type of information being sent. They contain a MIDI channel, to specifically direct the information, and a code that tells the device listening on that channel what type of data is about to follow. This prepares the device to receive any one of the following eight fundamental types of MIDI data messages: Note Off, Note On, Polyphonic Aftertouch, Control Change (a.k.a. continuous controller), Program Change, Channel Aftertouch, or System. The final type, system, refers broadly to system common, system real time, or system exclusive commands – these are not addressed to individual MIDI channels and the data bits normally used to specify MIDI channel are instead used to further specify the system message. Status bytes are usually followed by one or more data bytes that provide the actual information to be implemented.
Referenced words from today’s WFTD: MIDI, Byte, MIDI Channel, Note, Polyphonic, Aftertouch, Continuous Controller, Program Change, System Common, System, Real Time, and System Exclusive.