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

MIDI Musical Instrument Digital Interface (; MIDI) is an American-Japanese technical standard that describes a communication protocol, digital interface, and electrical connectors that connect a wide variety of electronic musical instruments, ...

-equipped electronic music hardware to

personal computer A personal computer, commonly referred to as PC or computer, is a computer designed for individual use. It is typically used for tasks such as Word processor, word processing, web browser, internet browsing, email, multimedia playback, and PC ...

s. It was designed by

Roland Corporation is a Japanese multinational manufacturer of electronic musical instruments, electronic equipment, and software. It was founded by Ikutaro Kakehashi in Osaka on 18 April 1972. In 2005, its headquarters relocated to Hamamatsu in Shizuoka Prefect ...

, 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 Apple II ("apple Roman numerals, two", stylized as Apple ][) is a series of microcomputers manufactured by Apple Computer, Inc. from 1977 to 1993. The Apple II (original), original Apple II model, which gave the series its name, was designed ...

* MIF-C64: For the Commodore 64 * MIF-FM7: For the Fujitsu FM-7 * 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 List of IBM Personal Computer models, IBM PC model line and the basis for the IBM PC compatible ''de facto'' standard. Released on ...

/ 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 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 8028 ...

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

/ IBM XT /

. 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-PC8: For the NEC PC-88 * MIF-PC98: For the

NEC PC-98 The , commonly shortened to PC-98 or simply , is a lineup of Japanese 16-bit and 32-bit personal computers manufactured by NEC from 1982 to 2003. While based on Intel processors, it uses an in-house architecture making it incompatible with IBM ...

* 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 ...

* MIF-AMG: For the

Amiga Amiga is a family of personal computers produced by Commodore International, Commodore from 1985 until the company's bankruptcy in 1994, with production by others afterward. The original model is one of a number of mid-1980s computers with 16-b ...

, from Musicsoft 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

/ IBM XT/

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

/ IBM XT/

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 Personal Computer, IBM PC, IBM Personal Computer XT, XT, IBM Personal Computer/AT, AT, and IBM PC Convertible, PC Co ...

Micro Channel architecture Micro Channel architecture, or the Micro Channel bus, is a proprietary hardware, proprietary 16-bit computing, 16- or 32-bit computing, 32-bit parallel communication, parallel computer bus (computing), bus publicly introduced by IBM in 1987 w ...

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 (it does not take up conventional memory). * S-MPU-IIAT (Super MPU II): for the IBM or compatible Plug and Play PC computers (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 (it does not take up precious conventional memory). * S-MPU/FMT: For

FM Towns The is a Japanese personal computer built by Fujitsu from 1989 to 1997. It started as a proprietary PC variant intended for multimedia applications and PC games, but later became more compatible with IBM PC compatibles. In 1993, the FM Towns ...

* LAPC-I: for the

and compatibles. Includes the Roland

CM-32L The Roland MT-32 Multi-Timbre Sound Module is a MIDI synthesizer module first released in 1987 by Roland Corporation. It was originally marketed to amateur musicians as a budget external synthesizer with an original list price of $695. However, ...

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

. Includes the Roland CM-32LN 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 (Roland Sound Canvas, Sound Canvas) is a Roland GS, GS MIDI sound module released in 1991 by Roland Corporation, Roland. The SC-55 was the first sound module to incorporate the new General MIDI standard. It was the first in the R ...

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

. 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

* Roland SCC-1, 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, were equipped with Roland chips whereas most had reverse-engineered ROMs (

Midiman M-Audio (formerly Midiman) is a business unit of inMusic Brands that designs and markets Audio interface, audio and Musical Instrument Digital Interface, MIDI interfaces, Electronic keyboard, keyboards and MIDI controllers, synthesizers, loudspea ...

/ Music Quest). Examples: *

MM-401 (8BIT, non Roland chip set, also sold as part of the Midiman PC Desktop Music Kit) *

Midi System, Inc. Musical Instrument Digital Interface (; MIDI) is an American-Japanese technical standard that describes a communication protocol, digital interface, and electrical connectors that connect a wide variety of electronic musical instruments, ...

MDR-401, non Roland chip set * Computer Music Supply CMS-401 (8BIT, non Roland chip set) * Music Quest PC MIDI Card / MQX-16s / MQX-32m (8 & 16BIT, non Roland chip set) * Voyetra V-400x / OP-400x (V-4000, V4001, 8BIT, Roland chip set) * MIDI LAND 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 peripheral 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 significant to ...

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 MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few op ...

. 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) 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, developed by USB Implementers Forum (USB-IF), for digital data transmission and power delivery between many types of electronics. It specifies the architecture, in particular the physical ...

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 connector The DIN connector is an electrical signal connector that was standardized by the (DIN), the German Institute for Standards, in the mid 1950s, initially with three pins for mono, but when stereo connections and gear appeared in the late 1950s, v ...

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, released five years earlier, which was then the longest time span between successive releases of Microsoft W ...

, a driver is available on

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

. As of 2011, the interface was still supported by

Linux Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...

and

Mac OS X macOS, previously OS X and originally Mac OS X, is a Unix, Unix-based operating system developed and marketed by Apple Inc., Apple since 2001. It is the current operating system for Apple's Mac (computer), Mac computers. With ...

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] {{DEFAULTSORT:Roland MPU-401 Computer hardware standards MIDI Obsolete technologies Music sequencers