RetroArch DOSBox Core: Source-Based Setup Guide

DOSBox is a multiplatform DOS emulator, and the libretro DOSBox core is authored by the DOSBox Team and licensed under GPLv2. This guide summarizes the official libretro documentation for the core: which file types it loads, how to generate and use config files, how to set up MIDI, and which core options are available.

Supported Content Formats

The DOSBox core can load content with the following file extensions: .exe, .com, .bat, and .conf. A DOS database is associated with the core.

Two Ways to Load Content

• 1. Loading an .exe, .com, or .bat file: the system directory is searched for a dosbox.conf file to load. If none is available, default values are used. This mode is equivalent to running a DOSBox binary with the specified file as the command line argument.
• 2. Loading a .conf file: DOSBox is loaded with the options in the config file. This mode is useful if you just want to be dropped at a command prompt, but it can also load a game by putting commands in the autoexec section.

For loading to be useful, the frontend needs keyboard and mouse support, and all keyboard shortcuts need to be remapped.

Generating a Config File

• 1. Create the DOSbox folder inside your libretro SYSTEM directory.
• 2. Load any DOS application.
• 3. Exit back to the command interpreter.
• 4. Run config -wcd.

Configuration files allow far better control than core options at this stage. According to the documentation, eventually every usable option will be exposed as a core option, but in the meantime combining both a config file and core options is described as the best alternative.

Autoexec Config Example

A generated default config is always loaded by default, but you can override it by saving custom settings, preferably in the game folder. The documentation gives this example config:

[autoexec]
@echo off
mount d "/storage/roms/dos/game"
d:
game.exe

You can store this config in the game folder (or any other directory) and load just the config instead of the exe file. Once you change a setting using the config command or via core options, you can update the config file by using config -wc.

MIDI Setup

To use MIDI, you need MT32_CONTROL.ROM and MT32_PCM.ROM in the system directory of RetroArch, then set the following:

[midi]
mpu401=intelligent
mididevice=mt32

Core Options

The core options below are shown in the core options menu. Defaults are bolded in the source documentation. The options under Enable advanced core-options are only shown when that option is enabled. CPU cycles are set as CPU cycles multiplied by the CPU cycle multiplier, plus CPU fine cycles multiplied by the CPU fine cycles multiplier in the advanced options.

Enable core-options (dosbox_use_options) controls whether the core options below are applied. Disable it to leave the settings to a loaded .conf file.

Controllers

The DOSBox core supports 6 ports. Ports 1 and 2 can be set to one of the following device types: Keyboard + Mouse, Gamepad, Joystick, or Disconnected. Ports 3 to 6 can be set to Keyboard + Mouse or Disconnected.

Keyboard Mapping Note

The documented keyboard mapping includes a notable swap: the RetroKeyboard Right input maps to the DOS Left arrow, and the RetroKeyboard Left input maps to the DOS Right arrow. Most other keys map directly, including letters, digits, function keys, and numpad inputs.