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When you hit a key on a MIDI keyboard, zero sound travels down the cable. Instead, the instrument sends a tiny packet of digital instructions telling another device exactly which note to play, how hard, and on which channel.
In 1983, synthesizer pioneers Dave Smith and Ikutaro Kakehashi introduced MIDI (Musical Instrument Digital Interface) to let instruments from competing manufacturers talk to each other seamlessly.
How do electronic instruments translate raw binary ones and zeros into musical performances?
The Anatomy of a MIDI Byte
MIDI 1.0 transmits data serially as 8-bit sequences called bytes. A byte consists of 8 binary digits (bits), but MIDI reserves the very first bit—the Most Significant Bit (MSB)—as a role identifier.
If the MSB is
1, it is a status byte (commands like Note-On or CC); if the MSB is 0, it is a data byte (values like pitch, velocity, or controller amount, spanning 0 to 127).📊Interactive diagram
Now that we know how bytes distinguish instructions from values, how does MIDI route different instruments along a single cable?
Channels and Note Messages
A Channel Voice Status byte encodes the message type in its upper nibble (bits 4–6, with bit 7 set to 1) and the target MIDI channel in its lower 4-bit nibble (bits 0–3, mapping binary values 00002 to 11112 to Channels 1 to 16).
A standard Note-On event is a 3-byte message: the status byte specifies Note-On and channel, followed by Data Byte 1 (key number 0–127, where 60 is Middle C), and Data Byte 2 (strike velocity 0–127).
📊Interactive diagram
Many keyboards send a Note-On with a velocity of 0 instead of a dedicated Note-Off status byte. Synthesizers treat zero velocity as an instruction to release the note, saving data bandwidth.