Roland MT-32¶

The Roland MT-32 multi-timbre sound module was released in 1987 by Roland Corporation, the iconic Japanese manufacturer of electronic musical instruments. It featured Roland’s novel, patented Linear Arithmetic (LA) Synthesis which combined sample playback with digital synthesis, capable of producing a wide range of realistic and synthesised sounds. As the little brother of Roland’s flagship Roland D-50 synthesiser released in the same year, it was aimed at the hobbyist musician market.

Around the same time, Sierra On-Line, the company most famous for pioneering the graphic adventure genre, was looking for ways to push PC audio to the next level. They took an interest in the MT-32, which lead to Sierra adding support for the module to most of their games from 1988 onwards. Other companies soon started following Sierra’s lead, which turned the Roland MT-32 a de facto standard for high-end audio in DOS gaming in the 1988 to 1992 period until General MIDI and CD Audio took over.

As the Roland MT-32 was considerably more expensive than other options, such as the AdLib, it remained out of reach for most computer users.

MT-32 variants¶

Roland produced several revisions and related models. Understanding the differences matters because some games sound different — or even malfunction — on the wrong revision.

Model	Year	`model` value	Key differences
MT-32 “old” (v1.0x)	1987	`mt32_old`	Original hardware; some games exploit firmware quirks
MT-32 “new” (v2.0x)	1987	`mt32_new`	Faster CPU, lower noise floor, revised instrument samples
MT-100	1988	—	MT-32 “new” with built-in sequencer
CM-32L	1989	`cm32l`	MT-32 “new” compatible + 33 extra sound effects
LAPC-I	1989	—	CM-32L on an ISA card (same ROMs)
CM-64	1989	—	CM-32L + CM-32P (added PCM instrument bank)

Choosing between “old” and “new”¶

The MT-32 was revised within its first year. The “new” revision (ROM v2.0x) has a faster CPU and lower background noise, but Roland also reorganised some of the instrument samples. Games composed on the original “old” hardware (ROM v1.0x) may sound subtly different on the “new” revision — certain instruments have a different timbre, and a few games exploit firmware quirks that were fixed in the newer ROMs.

As a rule of thumb:

Early Sierra games (1988–1990) — King’s Quest IV, Police Quest II, Space Quest III, Leisure Suit Larry ⅔ — were composed on “old” hardware and generally sound more authentic on mt32_old.
Games from 1991 onwards — and most LucasArts titles — work well on either revision.
When in doubt, the VOGONS Wiki compatibility list notes the recommended revision for each game.

The CM-32L¶

The Roland CM-32L released in 1989 — an MT-32 variant tailored for gaming — is generally the best overall choice. It is fully compatible with MT-32 “new” games and adds 33 extra sound effects (gunshots, explosions, dog barks, footsteps, etc.) that a handful of games use for enhanced audio. A few titles only sound complete on a CM-32L (e.g., Curse of Enchantia and Fire & Ice). LucasArts was one of the main game studios that typically took advantage of the extra sound effects of the module.

DOSBox Staging’s model = auto setting prefers the CM-32L when its ROMs are available, falling back to the best available MT-32 model otherwise. For early Sierra titles that sound best on “old” hardware, override with model = mt32_old in a per-game config.

MIDI before General MIDI¶

Important

Although the Roland MT-32 comes with a built-in library of 128 synth and 30 rhythm patches, it is a fully programmable synthesiser. Most games with MT-32 support take advantage of the module’s progammability and upload their own unique custom sounds at startup.

Most other sound modules that have so-called “MT-32 compatibility” modes can only emulate the built-in sounds; custom patches sound completely wrong on them. Even Roland’s own later sound modules suffer from the same problem. In short, most music composed for the Roland MT-32 only sounds correct when played back on a Roland MT-32, and nothing else.

Note

Roland MT-32 support might be referred to as Roland MT-100, LAPC-I (sometimes mispelled as LAPC-1), CM-32L, or CM-64 in the game’s setup program. All these refer to the same thing; you only need to research which ROM version is recommended for the game and set it accordingly.

Some games offer a Roland MT-32 with Sound Blaster option which should be generally preferred to the plain Roland MT-32 option as it might enable additional digital music to be played on the Sound Blaster.

Notable games with MT-32 support

Not all games that list “Roland MT-32” in their setup utility actually support it properly — and many games with excellent MT-32 music don’t advertise it prominently. The most reliable way to check is the community-maintained List of MT-32-compatible computer games on the VOGONS Wiki, which also notes which MT-32 model version works best for each title.

For a step-by-step walkthrough of setting up the MT-32 with a specific game, see the Beneath a Steel Sky chapter of the getting started guide.

DOSBox Staging emulates both the MT-32 sound module and the MPU-401 MIDI interface needed to communicate with it. The emulated MPU-401 supports the so-called Intelligent Mode, which most older games require (e.g., all older Sierra adventures). Most later games only need the much simpler UART Mode. Intelligent mode fully supports UART mode, so it’

[midi]
mididevice = mt32
mpu401 = uart

[mt32]
romdir = /path/to/mt32-roms

# Picks the CM-32L if available; best overall model except for old games
model = auto

# Early MT-32 games need this (e.g., older Sierra adventures)
model = mt32_old

Tip

Using the layering approach of DOSBox configuration files, you can pick one specific MT-32 model per game.

Roland ROM images¶

The emulation of the Roland MT-32 family of devices requires the ROM data from the original hardware to work.

Important

The Roland MT-32 ROM images are copyrighted by Roland Corporation, therefore they cannot be bundled with DOSBox. You need to provide these ROM files yourself to get any sound out of the MT-32 emulation.

ROMs are identified by their checksums, so file names do not matter. Both interleaved and non-interleaved ROM dumps are supported. Once you have acquired the necessary ROM sets, it’s recommended to copy them to the default ROM directory:

Platform	Default MT-32 ROM directory
Windows	`C:\Users\<USERNAME>\AppData\DOSBox\mt32-roms\`
macOS	`/Users/<USERNAME>/Library/Preferences/DOSBox/mt32-roms/`
Linux	`$HOME/.local/share/dosbox/mt32-roms/`

By doing so, you will make these ROMs globally available for all games.

Alternatively, you can create mt32-roms subfolders in your individual game folders to hold these ROMs, then DOSBox will find them when started from these game folders.

You can customise where DOSBox looks for these ROMs, see the romdir configuration setting for further details.

Supported ROM sets¶

The following ROM sets are supported. These originate from the MAME video game preservation project — learn more by searching for “mt32 mame roms” and “cm32l mame roms”.

Model	`model` value	Control ROM filename
CM-32L/LAPC-I v1.02	`cm32l_102`	`cm32l_control.rom`
CM-32L/LAPC-I 1.00	`cm32l_100`	`lapc-i.v1.0.0.ic3.bin`
MT-32 v2.04 (“new”)	`mt32_204` or `mt32_new`	`mt32_2.0.4.ic28.bin`
MT-32 v1.07 (“old”)	`mt32_107` or `mt32_old`	`mt32_1.0.7.ic26.bin` `mt32_1.0.7.ic27.bin`
MT-32 v1.06	`mt32_106`	`mt32_1.0.6.ic26.bin` `mt32_1.0.6.ic27.bin`
MT-32 v1.05	`mt32_105`	`mt32_1.0.5.ic26.bin` `mt32_1.0.5.ic27.bin`
MT-32 v1.04	`mt32_104`	`mt32_1.0.4.ic26.bin` `mt32_1.0.4.ic27.bin`
MT-32 BlueRidge	`mt32_bluer`	`blue_ridge__mt32a.bin` `blue_ridge__mt32b.bin`

Model	PCM ROM filename
MT-32 (all versions)	`r15449121.ic37.bin` `r15179844.ic21.bin` `r15179845.ic22.bin`
CM-32L (all versions)	`r15179945.ic8.bin`

Listing the installed ROMs¶

Run the MIXER /LISTMIDI command to see the list of available MT-32 ROMs:

In the above screenshot, mt32_107 is the currently active model. The green highlighted ‘y’ additionally indicates which directory will be used during the actual loading.

Warning

Both the control and PCM ROMs need to be present for a given model. If some model could not be detected, or you’re getting Failed to find ROMs for model <model_name> error at startup, make sure that both ROM sets have been copied to your ROM directory for that model.

ROM lookup paths¶

If romdir is not set, DOSBox Staging searches the following directories for MT-32 ROM files (in order). You can also place ROMs in an mt32-roms subfolder inside the game’s working directory.

Windows

%LOCALAPPDATA%\DOSBox\mt32-roms\
C:\mt32-rom-data\

macOS

~/Library/Preferences/DOSBox/mt32-roms/
~/Library/Audio/Sounds/MT32-Roms/
/usr/local/share/mt32-rom-data/
/usr/share/mt32-rom-data/

Linux

$XDG_DATA_HOME/dosbox/mt32-roms/ (defaults to ~/.local/share/dosbox/mt32-roms/)
$XDG_DATA_HOME/mt32-rom-data/ (defaults to ~/.local/share/mt32-rom-data/)
$XDG_DATA_DIRS/mt32-rom-data/ (defaults to /usr/local/share/mt32-rom-data/ and /usr/share/mt32-rom-data/)
$XDG_CONFIG_HOME/dosbox/mt32-roms/ (defaults to ~/.config/dosbox/mt32-roms/)

Mixer channel¶

The Roland MT-32 outputs to the MT32 mixer channel.

Configuration settings¶

Roland MT-32 settings are to be configured in the [mt32] section.

model¶

Roland MT-32/CM-32L model to use. You must have the ROM files for the selected model available (see romdir). The lookup for the best models is performed in order as listed.

Possible values:

auto default – Pick the best available model.
cm32l – Pick the best available CM-32L model.
mt32_old – Pick the best available “old” MT-32 model (v1.0x).
mt32_new – Pick the best available “new” MT-32 model (v2.0x).
mt32 – Pick the best available MT-32 model.
<version> – Use the exact specified model version (e.g., mt32_204).

Note

Run MIXER /LISTMIDI to see the list of available models.

romdir¶

The directory containing the Roland MT-32/CM-32L ROMs (unset by default). The directory can be absolute or relative, or leave it unset to use the mt32-roms directory in your DOSBox configuration directory. Other common system locations will be checked as well.

Note

The file names of the ROM files do not matter; the ROMs are identified by their checksums. Both interleaved and non-interleaved ROM files are supported.

mt32_filter¶

Filter for the Roland MT-32/CM-32L audio output.

Possible values:

off default – Don’t filter the output.
<custom> – Custom filter definition; see Custom filter settings for details.