The MPU-401, where ''MPU'' stands for MIDI Processing Unit, is an important but now obsolete interface for connecting

MIDI MIDI (; Musical Instrument Digital Interface) is a technical standard that describes a communications protocol, digital interface, and electrical connectors that connect a wide variety of electronic musical instruments, computers, and re ...

-equipped electronic music hardware to

personal computer A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or tec ...

s. It was designed by Roland Corporation, which also co-authored the MIDI standard. Roland MPU-401 (Ver

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 The Apple II (stylized as ) is an 8-bit home computer and one of the world's first highly successful mass-produced microcomputer products. It was designed primarily by Steve Wozniak; Jerry Manock developed the design of Apple II's foam-m ...

. * MIF-C64: For the

Commodore 64 The Commodore 64, also known as the C64, is an 8-bit home computer introduced in January 1982 by Commodore International (first shown at the Consumer Electronics Show, January 7–10, 1982, in Las Vegas). It has been listed in the Guinness ...

. * MIF-FM7: For the

Fujitsu FM7 The FM-7 ("Fujitsu Micro 7") is a home computer created by Fujitsu. It was first released in 1982 and was sold in Japan and Spain. It is a stripped-down version of Fujitsu's earlier FM-8 computer, and during development it was referred to as the ...

. * MIF-IPC: For the

IBM PC The IBM Personal Computer (model 5150, commonly known as the IBM PC) is the first microcomputer released in the IBM PC model line and the basis for the IBM PC compatible de facto standard. Released on August 12, 1981, it was created by a team ...

IBM XT The IBM Personal Computer XT (model 5160, often shortened to PC/XT) is the second computer in the IBM Personal Computer line, released on March 8, 1983. Except for the addition of a built-in hard drive and extra expansion slots, it is very simila ...

. 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 The IBM Personal Computer/AT (model 5170, abbreviated as IBM AT or PC/AT) was released in 1984 as the fourth model in the IBM Personal Computer line, following the IBM PC/XT and its IBM Portable PC variant. It was designed around the Intel 80 ...

, works with PC and XT as well. * Xanadu MUSICOM IFM-PC: For the

. This was a third party MIDI card, incorporating the MIF-IPC(-A) and additional functionality that was coupled with the OEM Roland MPU-401

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. It also had a mini audio jack on the PCB. * MIF-MSX: For the MSX. * MIF-PC8: For the NEC PC-88. * MIF-PC98: For the

NEC PC-98 The , commonly shortened to PC-98 or , is a lineup of Japanese 16-bit and 32-bit personal computers manufactured by NEC from 1982 to 2000. The platform established NEC's dominance in the Japanese personal computer market, and, by 1999, more th ...

. * MIF-X1: For the

Sharp X1 The , sometimes called the Sharp X1 or CZ-800C, is a series of home computers released by Sharp Corporation from 1982 to 1988. It is based on a Zilog Z80 CPU. The RGB display monitor for the X1 had a television tuner, and a computer screen co ...

. * MIF-V64: For the

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

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: *MPU-401N: an external interface, specifically designed for use with the

series notebook computers. This breakout-box unit features a special COMPUTER IN port for direct connection to the computer's 110-pin expansion bus. METRONOME OUT connector was added. Released in Japan only. * MPU-IPC: for the

and compatibles (8 bit ISA). It had a 25-pin female connector for the breakout box, even though only nine pins were used, and only seven were functionally different: both 5V and ground use two pins each. * MPU-IPC-T: for the

and compatibles (8 bit ISA). The MIDI SYNC connector was removed from this Taiwanese-manufactured model, and the previously hardcoded I/O address and IRQ could be set to different values with jumpers. The break-out box has three DIN connectors for MIDI (1xIN and 2xOUT) plus three 3.5mm mini jack connectors (TAPE IN, TAPE OUT and METRONOME OUT). * MPU-IMC: for the

IBM PS/2 The Personal System/2 or PS/2 is IBM's second generation of personal computers. Released in 1987, it officially replaced the IBM PC, XT, AT, and PC Convertible in IBM's lineup. Many of the PS/2's innovations, such as the 16550 UART (serial p ...

's Micro Channel Architecture bus. In earlier models both I/O address and IRQ were hardcoded to IRQ 2 (causing serious problems with the hard disk as it also uses that IRQ); in later models the IRQ could be set with a jumper. It had a 9-pin female connector for the breakout box. MPU-IMC IRQ Selection

. Due to the incompatibility of IRQ 2/9 (and potentially I/O addresses) between the MPU-IMC and IBM PS/2 MCA models certain games will not work with MPU-401. * S-MPU/AT (Super MPU): for the

and compatibles (16 bit ISA). It had a Mini-DIN female connector for the breakout box. The MIDI SYNC, TAPE IN, TAPE OUT, METRONOME OUT connectors was removed, but a second MIDI IN connector was added. An application to assign resources (plug and play) must be run to use the card in DOS. This application is not a TSR, i.e. it does not take up conventional memory. * S-MPU-IIAT (Super MPU II): for the IBM or compatible Plug and Play PC's (16 bit ISA). It had a Mini-DIN female connector for the breakout box with two MIDI In connectors and two MIDI Out connectors. An application to assign resources (plug and play) must be run to use the card in DOS. This application is not a TSR, i.e. it does not take up precious conventional memory. * LAPC-I: for the

and compatibles. Includes the

Roland CM-32L Roland (; frk, *Hrōþiland; lat-med, Hruodlandus or ''Rotholandus''; it, Orlando or ''Rolando''; died 15 August 778) was a Frankish military leader under Charlemagne who became one of the principal figures in the literary cycle known as the ...

sound source. A breakout box for this card, the MCB-1, was sold separately. * LAPC-N: for the

. Includes the

Roland CM-32LN Roland (; frk, *Hrōþiland; lat-med, Hruodlandus or ''Rotholandus''; it, Orlando or ''Rolando''; died 15 August 778) was a Frankish military leader under Charlemagne who became one of the principal figures in the literary cycle known as the ...

sound source. A breakout box for this card, the MCB-2, was sold separately. * RAP-10: for the

and compatibles (16 bit ISA). General midi sound source only. MPU-401 UART mode only. A breakout box for this card, the MCB-10, was sold separately. * SCP-55: for the IBM and compatible laptops (PCMCIA). Includes the

Roland SC-55 The Roland SC-55 ( Sound Canvas) is a GS MIDI sound module released in 1991 by Roland. The SC-55 was the first sound module to incorporate the new General MIDI standard. It was the first in the Roland Sound Canvas series. The SC-55 used both PC ...

sound source. A breakout box for this card, the MCB-3, was sold separately. MPU-401 UART mode only. 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

* MPU-APL: for the

series. Single-card combination of the MIF-APL interface and MPU-401, featuring MIDI IN, OUT, and SYNC connectors. * MPU-401AT: for

and "100% compatibles". Includes a connector for Wavetable daughterboards. * MPU-PC98: for the

. * MPU-PC98II: for the

. * S-MPU/PC (Super MPU PC-98): for the

. * S-MPU/2N (Super MPU II N): for the

. * SCC-1: for the

and compatibles. Includes the

sound source. * GPPC-N & GPPC-NA: for the

. Includes the Roland SC-55 sound source.

Clones

By the late 1980s other manufacturers of PCBs developed intelligent MPU-401 clones. Some of these, like

Voyetra The Turtle Beach Corporation (commonly referred to as Turtle Beach) is a gaming accessory manufacturer based in San Diego, California. The company has roots dating back to the 1970s where it developed sound cards, MIDI synthesizers, and various ...

, were equipped with Roland chips whereas others had retro-engineered ROMs (

Midiman M-Audio (formerly Midiman) is a business unit of inMusic Brands that designs and markets audio and MIDI interfaces, keyboards and MIDI controllers, synthesizers, loudspeakers, studio monitors, digital DJ systems, microphones, and music software ...

Music Quest Music is generally defined as the art of arranging sound to create some combination of form, harmony, melody, rhythm or otherwise expressive content. Exact definitions of music vary considerably around the world, though it is an aspect ...

). Examples: *

MM-401 (8BIT, non Roland chip set, also sold as part of the Midiman PC Desktop Music Kit) * Midi System, Inc. MDR-401, non Roland chip set * Computer Music Supply CMS-401 (8BIT, non Roland chip set) *

PC MIDI Card / MQX-16s / MQX-32m (8 & 16BIT, non Roland chip set) *

V-400x / OP-400x (V-4000, V4001, 8BIT, Roland chip set) *

MIDI LAND MIDI (; Musical Instrument Digital Interface) is a technical standard that describes a communications protocol, digital interface, and electrical connectors that connect a wide variety of electronic musical instruments, computers, and ...

DX-401 (non Roland chipset) & MD-401 (non Roland chipset) * Data Soft DS-401 (non Roland chipset) In 2015 hobbyists developed a Music Quest PC MIDI Card 8BIT clone. 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.

Modes

The MPU-401 can work in two modes, ''normal mode'' and ''

UART A universal asynchronous receiver-transmitter (UART ) is a computer hardware device for asynchronous serial communication in which the data format and transmission speeds are configurable. It sends data bits one by one, from the least signific ...

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, as implementing them in the host system's software became more efficient (than paying for dedicated hardware that will do them). As a result, the UART mode became the dominant mode of operation, with many clones not supporting the "intelligent mode" at all still being 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 the DOS operating system.

HardMPU

In 2015 a PCB (HardMPU) 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.

Contemporary interfaces

Physical MIDI connections are increasingly replaced with the

USB Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...

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 connector The DIN connector is an electrical connector that was standardized by the ' (DIN), the German Institute for Standards, in the early 1970s. The male DIN connectors (plugs) feature a 13.2 mm diameter metal shield with a notch that limits the ...

s. While MPU-401 support is no longer included in

Windows Vista Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, which was released five years before, at the time being the longest time span between successive releases of ...

, a driver is available on

Windows Update Windows Update is a Microsoft service for the Windows 9x and Windows NT families of operating system, which automates downloading and installing Microsoft Windows software updates over the Internet. The service delivers software updates for Wind ...

. As of 2011 the interface was still supported by

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which ...

and

Mac OS X macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and la ...

References

External links

'Card Times'
- Sound on Sound magazine, Nov 1996
SoftMPU

https://www.smartwheel.ca/airwheel-h3t-electric-smart-self-folding-wheel-chair-black-silver/ here] {{Roland Computer hardware standards MIDI Obsolete technologies Music sequencers