MPU-401
The MPU-401, where MPU stands for MIDI Processing Unit, was an important but now obsolete interface for connecting MIDI-equipped electronic music hardware to personal computers. It was designed by Roland Corporation, which also co-authored the MIDI standard.
Design
Released around 1984, the original MPU-401 was an external breakout box providing MIDI IN/MIDI OUT/MIDI THRU/TAPE IN/TAPE OUT/MIDI SYNC connectors, for use with a separately-sold interface card/cartridge ("MPU-401 interface kit") inserted into a computer system. For this setup, the following "interface kits" were made:
MIF-APL: For the Apple II.
MIF-C64: For the Commodore 64.
MIF-FM7: For the Fujitsu FM7.
MIF-IPC: For the IBM PC/IBM XT. It turned out not to work reliably with 286 and faster processors. Early versions of the actual PCB had IF-MIDI/IBM as a silk screen.
MIF-IPC-A: For the IBM AT, works with PC and XT as well.
Xanadu MUSICOM IFM-PC: For the IBM PC / IBM XT / IBM AT. This was a third party MIDI card, incorporating the MIF-IPC(-A) and additional functionality that was coupled with the OEM Roland MPU-401 BOB. It also had a mini audio jack on the PCB.
