MIDI won by giving every synth one common serial voice - an open standard.

By the early 1980s each synthesizer brand used its own proprietary control language, so a keyboard could not drive another maker's synth and studios were islands of incompatible gear.

Dave Smith of Sequential Circuits proposed a Universal Synthesizer Interface at the 1981 AES convention; Roland's Ikutaro Kakehashi and others pushed it forward, and the industry - US and Japanese makers together - evolved it into MIDI, published as MIDI 1.0 in 1983.

MIDI is deliberately simple: a serial line at 31.25 kbaud over a standard five-pin DIN connector carrying note on and off, pitch, and controller data. Because it was free and open, every manufacturer could implement it, and the format became the universal language of electronic music and, later, computer music production.

One serial voice every instrument can speak

It was a free, open, published standard, so competitors had no reason to build their own and no licence to pay.

A simple five-pin DIN serial interface at one speed was cheap to implement, so makers could add it without redesigning.

Interoperability meant one keyboard could drive any synth, so the value of every instrument rose and studios consolidated.

The public 1983 NAMM demonstration proved cross-vendor compatibility, which is what made a whole industry adopt it.

When a market fragments because each vendor's product cannot talk to the next, publish a simple, free protocol all of them can implement - the standard, not your product, becomes the platform.

MIDI became the standard connection for electronic instruments, drum machines, sequencers and computer music software, and it remains in essentially every synthesizer and controller decades later. The MIDI spec is maintained by the MIDI Manufacturers Association, and Dave Smith and the industry were recognised with a Technical Grammy.