MPU-401

The MPU-401, where MPU stands for MIDI Processing Unit, is an important but now obsolescent standard for MIDI interfaces on the PC platform. It was designed by the Roland Corporation, which also co-authored the MIDI standard.

Released around 1984, the original MPU-401 was a board to be inserted into a computer and an external box with connectors and some processing intelligence intended to offload the CPU. Different boards could presumably exist, depending on the system bus of the host computer; it is uncertain whether Roland actually manufactured non-PC boards.

The MPU-401 can work in two modes, smart and dumb UART. Only the UART mode has been used since the end of the 1980's, as the smart mode is difficult to setup, not so useful with today's fast computers and only implemented in fully compatible clones (for example those manufactured by MusicQuest ).

The current trend in MIDI world is to use the USB interface, and a USB to MIDI converter in order to drive musical peripherals which do not yet have their own USB ports. Often, peripherals are able to accept MIDI input through USB and route it to the traditional DIN connectors.