El Reg is doing a feature on the occasion of the 30th birthday of MIDI 1.0, the specification of which was published in August 1983. Luckily for us, they know their history so Part Two mentions that "MIDI on computers happened very early on in its development, with Yamaha adapting the MSX for music" and describes the Yamaha YIS-503 and CX5M.
Relevant link: The Register on MSX's role in the history of MIDI
