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MIDI¶

Between about 1988 and 1994, MIDI music was the ultimate high-end audio option in DOS gaming, offering never-heard-before realism and CD quality audio fidelity. Not many could afford the high price tag of MIDI sound modules back in the day — they often sold for 3 to 5 times higher as a Sound Blaster card. But thanks to the wonders of emulation, now all DOS enthusiasts can experience MIDI music nirvana in its full glory!

Because MIDI plays such a pivotal role in DOS gaming history, it is important to understand its origins and how it works at a basic level.

A brief introduction to MIDI¶

The MIDI standard (Musical Instrument Digital Interface) was created in the early 1980s to allow audio equipment from different manufacturers to communicate with each other. Originally aimed at the professional market, it soon found its way into home studios and computer games thanks to the home computer revolution.

MIDI is essentially a communication protocol. When you press a key on a MIDI keyboard, a short message is sent to a sound module instructing it to play a certain instrument at a certain pitch. Because the communication is digital, the keyboard can be replaced with a computer — a MIDI sequencer program can send thousands of precisely timed messages, controlling a full orchestra’s worth of instruments.

MIDI compositions are best viewed as the computer music equivalent of sheet music — a MIDI score only contains note data and abstract descriptions of the instruments, while the sound module is responsible for generating the actual sounds using its on-board samples or synthesis capabilities.

MIDI in DOS gaming¶

In the beginning, all DOS games came on floppies. Even if a game came on 10 floppies or more, there was simply not enough space for long musical pieces stored as digital audio! Given that MIDI scores take very little disk space compared to digital audio (generally, just a few tens of kilobytes per composition), MIDI music was an ideal match for DOS games before the wide-spread adoption of the CD-ROM with its huge 650 to 700 megabytes of capacity on a single CD. This is similar in principle to how the Creative Music System and AdLib synthesisers were used in games, only these MIDI sound modules were capable of producing much higher quality music using sampled sounds of real-world instruments.

DOS games featuring MIDI music support either or both of the following two major MIDI standards:

  • Roland MT-32 and variants — Released in 1987, this module was the only option for MIDI music in DOS games until about 1992. Most notably, you need the MT-32 for the best music in older Sierra and LucasArts adventure games.

  • General MIDI — The world’s first General MIDI capable module, the Roland Sound Canvas SC-55, was released 1991. Games started adding General MIDI support from about 1992 onwards, which resulted in the MT-32 losing most of its relevance by the mid-90s.

You can read more about these modules in their respective documentation sections.

Many games support multiple MIDI devices, and the best choice is not always obvious. The community-maintained List of MT-32-compatible computer games on the VOGONS Wiki is the definitive reference for which MIDI device to use with each game. There is no other reliable way to know for sure — game manuals and setup utilities often omit or misrepresent MIDI support.

Roland MPU-401 MIDI interface¶

Initially, you had to buy the Roland MPU-401 MIDI interface to connect an external MIDI sound module to your PC. This was an external box connected to your PC which then you hooked up to another external box, your sound module. Later on, sound cards started incorporating integrated MPU-401 compatible interfaces, so you could connect the sound module directly to your sound card.

DOSBox Staging emulates a Roland MPU-401 compatible MIDI interface which is enabled by default. The emulated MPU-401 operates in the so-called Intelligent Mode out-of-the-box; this provides certain extra features many older games depend on. The other, more recent mode is UART Mode. Older titles often require Intelligent Mode, most more recent ones work fine with either.

See mpu401 for more details.

Setting up MIDI¶

MIDI related settings are to be configured in the [midi] section. The most common usage scenario is to leave mididevice at its default auto setting, then set midiconfig to:

  • mt32 to use the built-in Roland MT-32 emulation,
  • fluidsynth to use the built-in FluidSynth MIDI synthesiser,
  • or to an ID that identifies an external MIDI device.

You can use the mixer /listmidi DOS command to see the list of available external MIDI devices.

Tip

To easily switch between a built-in and an external MIDI device per game (typically between the built-in MT-32 emulation and Roland’s Sound Canvas VA running in an external MIDI host program), you can use the layered configuration approach to your advantage.

As an example, to easily switch between the built-in MT-32 emulation and an external MIDI device that contains “loopMIDI” in its name, put this into your global configuration:

[midi]
mididevice = mt32
midiconfig = loopMIDI

Without any futher MIDI configuration in your local DOSBox config, this will default to using the built-in Roland MT-32 emulation. To switch to the external MIDI device, set mididevice to auto in your local config:

[midi]
mididevice = auto

Using external MIDI hardware¶

If you own a physical MIDI sound module (an MT-32, SC-55, or similar), you can connect it to your computer and have DOSBox Staging send MIDI data directly to it. This is the ultimate option for enthusiasts who want authentic hardware playback.

You’ll need a USB MIDI interface (e.g., Roland UM-ONE mk2) to connect the module to a modern computer. The MIDI cable carries note data only — you’ll also need audio cables from the module’s line outputs to your speakers or audio interface.

To set it up:

  • Connect the USB MIDI interface and power on the sound module.
  • Run MIXER /LISTMIDI at the DOSBox DOS prompt to list available MIDI devices and find your interface’s name or ID.
  • Set mididevice to port and midiconfig to the device name (or numeric ID):
[midi]
mididevice = port
midiconfig = UM-ONE

Name-based identification is preferred over numeric IDs, as the numbers can change when you unplug and reattach USB devices.

Configuration settings¶

MIDI related settings are to be configured in the [midi] section.

mididevice¶

Selects the MIDI device where data from the emulated MPU-401 MIDI interface is sent.

Possible values:

  • port default — A MIDI port of the host operating system’s MIDI interface. You can configure the port to use with the midiconfig setting.

  • fluidsynth — The built-in FluidSynth MIDI synthesiser (SoundFont player). See the FluidSynth configuration settings for further details.

  • mt32 — The built-in Roland MT-32 synthesiser. See the Roland MT-32 configuration settings for further details.

  • soundcanvas — The internal Roland SC-55 synthesiser (requires a CLAP audio plugin). See the Sound Canvas configuration settings for further details.

  • coreaudio (macOS only) — Use the built-in macOS MIDI synthesiser. The SoundFont to use can be specified with midiconfig.

  • none — Disable MIDI output.

midiconfig¶

Configuration options for the selected MIDI device.

Depending on the mididevice setting, the midiconfig setting is interpreted as follows:

mididevice setting midiconfig setting
none N/A
fluidsynth N/A
mt32 N/A
auto
  • mt32 — Use the built-in MT-32 synthesiser
  • fluidsynth — Use the built-in FluidSynth MIDI synthesiser
  • ID [delaysysex] — Use MIDI device external to DOSBox with this ID. The delaysysex option might be needed for some older external MIDI modules.
coreaudio Name of the SoundFont to use.
coremidi N/A

In auto mode, the ID can be either the numeric identifier of the MIDI device (MIDI port) or a part of its name. Using the name-based identification is preferable as the numbers can change if you unplug then reattach your external MIDI adapters or audio interfaces.

Use the mixer /listmidi command to list the IDs and names of all MIDI devices available on your system.

Important

If you’re using a physical Roland MT-32 with revision 0 PCB, the hardware may require a delay in order to prevent its buffer from overflowing. In that case, add delaysysex, e.g., midiconfig = 2 delaysysex.

mpu401¶

MPU-401 MIDI interface mode to emulate.

Possible values:

  • none — Disable MPU-401 emulation.

  • intelligent default — The intelligent mode was present on the original MPU-401 manufactured by Roland and on some clones. It provides MIDI sequencer features and a precise MIDI event sending mechanism via timestamped messages among a few other things. Applications could offload MIDI-related tasks, freeing up slow CPUs to do other tasks. Earlier MT-32 games depend on these features and will not produce sound in uart mode.

  • uart — Use UART mode of the MPU-401 that simply forwards each byte written to the MPU to the MIDI device in real-time. Sound Blaster cards can only operate in UART mode, and virtually all General MIDI games require only UART mode.

raw_midi_output¶

Enable raw, unaltered MIDI output (off by default). The MIDI drivers of many games don’t fully conform to the MIDI standard, which makes editing their MIDI recordings error-prone in MIDI sequencers. DOSBox corrects the MIDI output of such games by default with no audible difference; it only affects the data representation.

Only enable this if you need to capture the raw, unaltered MIDI output of a program, e.g., when working with music applications or debugging MIDI issues.

Possible values: on, off default