How MIDI Began
A serial agreement from 1983 that describes pitch, touch and switches in three bytes.
Related
MIDI is neither a sound nor a file format but an agreement about describing performance actions. Before 1983, every synth had its own interface.
The problem
Two devices had to agree on voltage, scanning and time. Without a shared language, pitch and touch were matched by ear, and every new machine started over.
Protocol or message
Sequential Circuits proposed a scheme in 1981, and MIDI 1.0 appeared in 1983 from the MMA and JMSC. Its physical layer is a five-pin DIN current loop at 31,250 bits per second, isolated by an opto-coupler. Data bytes carry seven bits, the top bit reserved for status. Notes, velocity, program changes and clock queue on one wire. Sixteen channels let a controller address several parts.
Settings and practice
Connect MIDI OUT to MIDI IN; THRU forwards unchanged. Long chains accumulate delay, so use a splitter beyond three devices. When two devices want to be clock master, keep one source. Old gear understands channel messages, so skip SysEx at first.
What to listen for
Move the performance to another sound source and pitch and tempo remain, while timbre and the velocity curve change. The protocol preserves the action, not the sound.
Common misunderstandings
MIDI is not audio and the cable carries no sound. A MIDI file is not a waveform. Messages from 1983 still work, and newer versions widen the numbers.
Listen in the library
All tracks from midicn-lib — inline badge is the license tier (C1 commercial / C2 non-commercial / C3 study only).
Sources
- MIDI 1.0 规范对物理层、串行速率与消息格式的定义，依 MMA 公开规范核查，未抄文本
- 1983 年规范发布前后的行业协作背景，依公开技术史料核查，未抄文本
Used for fact-checking only; all prose is original.