Roland MPU-401 (top-cover removed).

The MPU-401, where MPU stands for MIDI Processing Unit, is 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.[1]

A Logo replica of the MPU-401
Logo replica of the MPU-401

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:

In 2014 hobbyists built clones of the MIF-IPC-A card for PCs.[11]

Variants

Later, Roland would put most of the electronics originally found in the breakout box onto the interface card itself, thus reducing the size of the breakout box. Products released in this manner:

Still later, Roland would get rid of the breakout box completely and put all connectors on the back of the interface card itself. Products released in this manner:

Roland MPU-IMC, the rare 'Micro Channel' version of the card.
Roland MPU-401AT
Roland MPU-PC98II
Roland MPU-IPC-T card

Clones

By the late 1980s other manufacturers of PCBs developed intelligent MPU-401 clones. Some of these, like Voyetra, were equipped with Roland chips whereas most had reverse-engineered ROMs (Midiman / Music Quest).[18][19]

Examples:

In 2015 hobbyists developed a Music Quest PC MIDI Card 8BIT clone.[27] In 2017/2018 hobbyists developed a revision of the Music Quest PC MIDI Card 8BIT clone that includes a wavetable header in analogy of the Roland MPU-401AT.[28]

Modes

The MPU-401 can work in two modes, normal mode and UART mode. "Normal mode" would provide the host system with an 8-track sequencer, MIDI clock output, SYNC 24 signal output, Tape Sync and a metronome; as a result of these features, it is often called "intelligent mode". Compare this to UART mode, which reduces the MPU-401 to simply relaying in-/outcoming MIDI data bytes.

As computers became more powerful, the features offered in "intelligent mode" became obsolete. Implementing these in the host system's software was more efficient. Specific hardware was no longer required. As a result, the UART mode became the dominant mode of operation. Early UART MPU-401 capable cards were still advertised as MPU-401 compatible.

SoftMPU

In the mid 2010s, a hobbyist platform software interface, SoftMPU, was written that upgrades UART (non intelligent) MPU-401 interfaces to an intelligent MPU-401 interface, however this only works for MS-DOS.[29] It also does not work for all games. Especially early Sierra games, such as Jones in the Fast Lane, will not work with SoftMPU.

HardMPU

In 2015, a PCB (HardMPU)[30] was developed that incorporates SoftMPU as logic on hardware (so that the PC's CPU does not have to process intelligent MIDI). Currently HardMPU only supports playback and not recording.[31]

Contemporary interfaces

Physical MIDI connections are increasingly replaced with 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 convert it for the traditional DIN connectors. While MPU-401 support is no longer included in Windows Vista, a driver is available on Windows Update.[32] As of 2011, the interface was still supported by Linux and Mac OS X.

References

  1. ^ Souvignier, Todd. Alfred's Teach Yourself Computer Audio. Alfred Music. p. 79. ISBN 978-1-4574-2002-3.
  2. ^ "【送ネコポス250円】Roland MIF-FM7 FM-7用MIDIカード カードのみで外付けBOX欠". Retrieved 27 January 2024.
  3. ^ a b "Nerdly Pleasures: Tutorial : How to Get the Roland MT-32 working with DOS Games". March 21, 2010.
  4. ^ "Roland MPU-401 Special Midi Interface with Dual Boot Computer". eBay. Archived from the original on February 13, 2018.
  5. ^ Winn L. Rosch (1986-10-14). "Musical Interludes With the PC". PC Magazine: 265–281.
  6. ^ David Ellis (November 1986). "Musicom". Music Technology.
  7. ^ "ジャンク MIDI PROCESSING UNIT Roland MPU-401,... - ヤフオク!". ヤフオク! (in Japanese). Archived from the original on October 4, 2018.
  8. ^ "Roland MPU-401 & MIF-X1 INTERFACE KIT X1 series". Buyee.
  9. ^ "Roland MPU-401 & MIF-X1 INTERFACE KIT X1 series の落札情報". Retrieved 27 January 2024.
  10. ^ "MIX BOOKSHELF, WINTER 1987-88" (PDF). Retrieved 27 January 2024.
  11. ^ "Cloning an MIF ISA Card". www.amibay.com.
  12. ^ "Roland MPU-IMC". ps-2.kev009.com.
  13. ^ "MPU-IMC on the MT-32 (issues with certain games)". www.vogons.org.
  14. ^ "S-MPU/FMT Manual" (PDF). Retrieved 27 January 2024.
  15. ^ "Roland Super MPU MIDIプロセシングユニットS-MPU/FMT". Retrieved 27 January 2024.
  16. ^ "Roland Corporation - SCP-55 - Owner's Manual". www.synthmanuals.com.
  17. ^ "Roland GS History". xv2020.s14.xrea.com.
  18. ^ "Bought these (retro) hardware today - Page 215". www.vogons.org.
  19. ^ "MIDI Land INC DX-401". www.vogons.org.
  20. ^ "Vintage midimanPC Desktop Music Kit MM-401 MIDI interface w/ software". eBay. Archived from the original on January 22, 2019.
  21. ^ "MIDI for the 486 with a MDR-401". 30 November 2021.
  22. ^ "Ds-401 8 bit Midi Interface card Jumper settings \ VOGONS".
  23. ^ https://www.vogons.org/viewtopic.php?f=62&t=96904
  24. ^ "Computer Music Supply CMS-401 (1988) 8bit MIDI interface card". oldschooldaw.com. September 13, 2018. Archived from the original on September 13, 2018.((cite web)): CS1 maint: unfit URL (link)
  25. ^ "Bought these (retro) hardware today - Page 1255". www.vogons.org.
  26. ^ "Ds-401 8 bit Midi Interface card Jumper settings". www.vogons.org.
  27. ^ "Music Quest MPU clone cards, anyone interested in them?". www.vogons.org.
  28. ^ "Sold ISA 100% Roland compatible MPU interfaces , new version with Wavetable header". www.amibay.com.
  29. ^ "SoftMPU". www.vogons.org.
  30. ^ "ab0tj/HardMPU". August 31, 2020 – via GitHub.
  31. ^ "HardMPU, anyone?". www.vogons.org.
  32. ^ "Microsoft Update Catalog". www.catalog.update.microsoft.com.