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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 cost 3 to 5 times as much 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.

The General MIDI standard¶

General MIDI (GM) was introduced in 1991 to solve a simple but annoying problem: MIDI could tell a synthesiser what notes to play, but not which instruments to use. GM standardised the instrument assignments — program number 1 is always an acoustic grand piano, program 41 is always a violin, and so on — so that music written for one GM device would sound recognisable on any other.

The Roland SC-55, released the same year, was the first Sound Canvas module and quickly became the de facto standard for DOS game music. Roland’s own GS (General Standard) extension sat on top of GM, adding extra instruments, percussion kits, and digital effects while remaining fully backwards-compatible with the core GM specification.

Most DOS game composers wrote and tested their music on Roland Sound Canvas hardware. Games like Monkey Island 2, Ultima VII, Doom, and Duke Nukem 3D all sound their best when played through an SC-55 or a compatible device. Since different GM manufacturers recorded their own instrument samples, playback can sound noticeably different from one device to another, but the SC-55 is the gold standard for hearing the music as the composer intended.

The Yamaha DB50XG and MU-series (MU50, MU80, MU100, etc.) are alternative MIDI modules that offer excellent SC-55 compatibility with a more modern and punchy sonic character. Many enthusiasts prefer them to the SC-55 in certain games. For a detailed comparison of how these modules stack up against the SC-55, see this article.

The MT-32 to General MIDI transition¶

MIDI sound in DOS games evolved through three distinct periods:

  • 1987–1991: MT-32 era — The Roland MT-32 was the only MIDI option. Sierra On-Line, LucasArts, and Origin Systems led the way with dedicated MT-32 music.
  • 1991–1993: transition — The SC-55 and General MIDI standard arrived. Many games supported both MT-32 and GM, giving players a choice. Games like Indiana Jones and the Fate of Atlantis and Star Wars: X-Wing sound excellent on either device.
  • 1993 onwards: GM dominance — General MIDI became the standard. MT-32 support faded as the SC-55 was cheaper, more widely available, and standardised. By 1995, very few new games included MT-32 support.
Notable games with General MIDI support

Which MIDI device should I use?¶

DOSBox Staging offers three main ways to get MIDI playback:

Determining whether a game supports the Sound Canvas (General MIDI), the Roland MT-32, or both is not always obvious from the setup utility alone. The community-maintained List of MT-32-compatible computer games on the VOGONS Wiki is the most comprehensive reference for which MIDI devices each game supports and which produces the best results. There is no other reliable way to know for sure — game manuals and setup utilities often omit or misrepresent MIDI support.

As a rough rule of thumb:

  • Pre-1992 games (especially Sierra and LucasArts adventures) — try Roland MT-32 first.
  • 1992–1993 games — check the VOGONS list; many sound excellent on either the MT-32 or General MIDI.
  • Post-1993 games — almost always General MIDI. Use Sound Canvas emulation for the most authentic results, or FluidSynth as a lighter alternative.

Roland MT-32 is not General MIDI

Do not confuse the Roland MT-32 family of MIDI sound modules with General MIDI modules! Music composed for the MT-32 often sounds utterly wrong on a General MIDI device, and vice versa. Yes, they both have “MIDI” in their names, but that only refers to the MIDI communication protocol. The MT-32 range of devices are programmable synthesisers, and most MT-32 supporting games take advantage of that to create custom sounds. In contrast, General MIDI modules feature more realistic-sounding real-world instruments with a standardised sound set.

Quite confusingly, there is a large list of games that claim MT-32 compatibility but only sound correct on a General MIDI module. Make sure to check the List of games that falsely claim MT-32 compatibility as well before configuring a game for MT-32 sound.

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. Set the mididevice setting to select which MIDI device to use:

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 further 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 devices¶

DOSBox Staging can send MIDI data to any MIDI device outside of its own built-in synthesisers. This includes physical hardware modules connected via USB, but also software synthesisers running on your machine — anything that appears as a MIDI port to the operating system.

Physical MIDI devices¶

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.

Virtual MIDI devices¶

You can also route DOSBox’s MIDI output to another software synthesiser running on your machine (such as Roland’s Sound Canvas VA, or any DAW or standalone synth plugin) by using a virtual MIDI loopback driver. This creates a virtual MIDI cable that connects DOSBox’s output to the other program’s input.

  • Windows — loopMIDI or loopBE create virtual MIDI ports. Install one, create a port, then point your external synthesiser at that port for input and set midiconfig to the port name in DOSBox.
  • macOS — Use the built-in IAC Driver in Audio MIDI Setup to create virtual MIDI ports, or use a third-party tool.
  • Linux — ALSA’s snd-virmidi module or JACK MIDI can create virtual ports.

Finding your MIDI device¶

Run MIXER /LISTMIDI at the DOSBox DOS prompt to list all MIDI output ports available on your system. Set mididevice to port and midiconfig to the device name:

[midi]
mididevice = port
midiconfig = UM-ONE

You don’t need to type the full device name — DOSBox Staging performs a case-insensitive substring match against all available MIDI port names. For example, midiconfig = UM-ONE will match a port called “Roland UM-ONE MIDI 1”. If multiple ports match, the first match is used. You can also use the numeric port ID shown by MIXER /LISTMIDI, but name-based identification is preferred as the numbers can change when you unplug and reattach USB devices.

[midi]
mididevice = port
midiconfig = 2

Platform-specific MIDI¶

DOSBox Staging uses the native MIDI subsystem on each platform:

  • macOS — Uses Apple’s CoreMIDI framework. All MIDI destinations visible in Audio MIDI Setup (including virtual ports from apps like loopMIDI or DAWs) are available. Use MIXER /LISTMIDI to see the list.

  • Linux — Uses ALSA sequencer ports. You can specify the port by name or by ALSA address (e.g., midiconfig = 14:0). ALSA prioritises synthesiser-type ports when matching by name.

  • Windows — Uses the standard Windows MIDI API. All MIDI output devices registered with the system appear in MIXER /LISTMIDI. If no device is specified, DOSBox uses the Windows MIDI Mapper (the system default).

macOS CoreAudio synthesiser¶

On macOS, DOSBox Staging provides a coreaudio MIDI device option that uses Apple’s built-in DLS synthesiser. Although not a physical external device, it is external to DOSBox — the audio is rendered by macOS’s own Audio Unit synthesiser, bypassing DOSBox’s mixer entirely. You can optionally point it at a SoundFont file:

[midi]
mididevice = coreaudio
midiconfig = /path/to/soundfont.sf2

The default Apple DLS sound set is fairly basic; loading a good SoundFont improves results significantly.

SysEx delays for older hardware¶

Some older MIDI modules (notably the Roland MT-32 with revision 0 PCB) can overflow their internal buffers when receiving large System Exclusive (SysEx) messages. If you experience garbled patches or missing instruments, add delaysysex after the device identifier:

[midi]
mididevice = port
midiconfig = UM-ONE delaysysex

This adds a small calculated delay between SysEx messages to prevent buffer overflows.

MIDI output corrections¶

By default, DOSBox Staging corrects common MIDI protocol errors in the output of DOS games. Many games send “All Notes Off” messages instead of proper per-note Note Off commands. DOSBox converts these to individual Note Off messages for each active note, which prevents hanging notes and makes recorded MIDI data easier to edit in a sequencer. This also fixes the infamous hanging notes issue with the Roland RA-50 external MIDI module, which does not implement the “All Notes Off” message at all.

The raw_midi_output setting disables these corrections. This produces no audible difference on most synthesisers — it only affects how the MIDI data stream is represented. Enable it if you need the unmodified MIDI output for debugging, working with music applications, or when an external hardware or MIDI recording setup requires the unprocessed stream.

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. See Using external MIDI devices for details.

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

  • mt32 — The built-in Roland MT-32 synthesiser. See Roland MT-32 for details.

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

  • coreaudio (macOS only) — Use the built-in macOS CoreAudio synthesiser. See macOS CoreAudio synthesiser for details. 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
soundcanvas N/A
port ID [delaysysex] — Use the MIDI device with this ID. The ID can be a numeric port index or a part of the device name (case-insensitive substring match). The delaysysex option might be needed for some older external MIDI modules.
coreaudio Path to the SoundFont to use.

With mididevice = port, using name-based identification is preferable as the numeric IDs 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, precise event timing via timestamped messages, and the ability to offload MIDI-related tasks from slow CPUs. 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