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DOSBox is controlled by a file called dosbox.conf. Game-specific files can also be designed and loaded using command line switches.

Below are the default values of all settings in dosbox.conf, and what values you can change them to. A word written like this indicates a term to type, while one written like <this> indicates a wide number of values you can define.

Contents 1 SDL 2 DOSBox 3 Render 4 CPU 5 Mixer 6 MIDI 7 Sblaster 8 GUS 9 PC Speaker 10 Joystick 11 Serial 12 DOS 13 IPX 14 autoexec 14.1 Mounting a virtual hard drive 14.2 Mounting an optical drive 14.3 Starting drive letter 14.4 Other commands

[edit] SDL

setting=default	choices	explanation
fullscreen=false	true, false	start DOSBox directly in fullscreen.
fulldouble=false	true, false	Use double buffering in fullscreen.
fullresolution=original	original, <dimensions>	fullscreen resolution. Can be set to anything you like.
windowresolution=original	original, <dimensions>	Scale the window to this size IF the output device supports hardware scaling.
output=surface	surface, overlay, opengl, openglnb, ddraw	what rendering method to use for video output. Different settings affect performance in different ways.
autolock=true	true, false	Mouse will automatically lock once you click inside the DOSBox window.
sensitivity=100	<number>	Mouse sensitivity. 100 is the default and should be fine.
waitonerror=true	true, false	Wait before closing the console if DOSBox has an error.
priority=higher,normal	<active>,<inactive>	Priority levels; "active" is for when the window is open, "inactive" is for when the window is minimised or not in focus. Possible priorities are lowest, lower, normal, higher, highest, pause.
mapperfile=mapper.txt	<filename.txt>	File used to load/save the key/event mappings.
usescancodes=true	true, false	Avoid usage of symkeys, might not work on all operating systems.

[edit] DOSBox

setting=default	choices	explanation
language=	<filename>	define another language file. Useless if English is your native language, or you are sufficiently fluent.
machine=vga	hercules, cga, tandy, pcjr, vga	The type of machine to emulate
captures=capture	<folder name>	Directory where things like wave, midi, and screenshots get captured.
memsize=16	<number>	Amount of memory dosbox has (in megabytes).

[edit] Render

setting=default	choices	explanation
frameskip=0	<number>	How many frames to skip before drawing one. Increasing the frameskip will help increase overall emulation speed significantly, but will result in jerkier visuals.
aspect=false	true, false	aspect correction. If your output method doesn't support scaling this will affect the speed.
scaler=normal2x	<scaler>	scalers to enlarge or enhance the graphics. Possible scalers are none, normal2x, normal3x, advmame2x, advmame3x, hq2x, hq3x, 2xsai, super2xsai, supereagle, advinterp2x, advinterp3x, tv2x, tv3x, rgb2x, rgb3x, scan2x, scan3x.

[edit] CPU

setting=default	choices	explanation
core=auto	normal, simple, dynamic, auto	CPU Core used in emulation; auto switches from normal to dynamic if appropriate.
cycles=auto	auto, <number>	Amount of instructions to emulate each millisecond. Setting this too high results in sound dropouts and lags. You can also let DOSBox guess the correct value by setting it to max. The default setting (auto) switches to max if appropriate.
cycleup=500	<number>	number of cycles to increase when using the key combo.
cycledown=20	<number>	number of cycles lowered when using the key combo. Setting it lower than 100 will be a percentage.

[edit] Mixer

setting=default	choices	explanation
nosound=false	false, true	sound muted but still emulated.
rate=22050	11025, 22050, 44100	mixer sample rate. Setting other devices higher than this value may actually lower their sound quality.
blocksize=2048	512, 1024, 2048, 3072, 4096	Mixer block size. Larger blocks might help sound stuttering but will increase sound lag and system drain.
prebuffer=10	<number>	How many milliseconds of data to keep on top of the blocksize.

[edit] MIDI

setting=default	choices	explanation
mpu401=intelligent	none, uart, intelligent	Type of MPU-401 to emulate.
device=default	default, alsa, oss, win32, coreaudio, none	Device that will receive the MIDI data from the MPU-401.
config=	<config>	Special configuration options for the device. In Windows put the ID of the device you want to use.

[edit] Sblaster

setting=default	choices	explanation
sbtype=sb16	none, sb1, sb2, sbpro1, sbpro2, sb16	Type of Sound Blaster to emulate. For most games use sb16. If a game's configuration supports pro, try one of the pro settings.
sbbase=220	210, 220, 240, 260, 280	the base I/O address of the Sound Blaster.
irq=7	3, 5, 7, 10, 11	the IRQ address of the Sound Blaster.
dma=1	0, 1, 3	the DMA address of the Sound Blaster.
hdma=5	5, 6, 7	the HDMA address of the Sound Blaster.
mixer=true	true, false	Allow the Sound Blaster mixer to modify the DOSBox mixer.
oplmode=auto	auto, cms, opl2, dualopl2, opl3	Type of OPL emulation. On auto the mode is determined by the Sound Blaster type. All OPL modes are 'Adlib', except for CMS.
oplrate=22050	11025, 22050, 44100	Sample rate of OPL music emulation.

[edit] GUS

setting=default	choices	explanation
gus=true	true, false	Gravis Ultrasound emulation on/off.
gusrate=22050	11025, 22050, 44100	Sample rate of Ultrasound emulation.
gusbase=240	210, 220, 240, 260, 280	the base I/O address of the Gravis Ultrasound
irq1=5	3, 5, 7, 10, 11	the IRQ address of the Gravis Ultrasound
irq2=5	3, 5, 7, 10, 11	the IRQ address of the Gravis Ultrasound (alternate; can be same as above)
dma1=3	0, 1, 3	the DMA address of the Gravis Ultrasound
dma2=3	0, 1, 3	the DMA address of the Gravis Ultrasound (alternate; can be same as above)
ultradir=C:\ULTRASND	<path>	Ultrasound directory. Patch files for GUS playback go here.

[edit] PC Speaker

setting=default	choices	explanation
pcspeaker=true	true, false	PC Speaker emulation. Note that the sound will come through your speakers, rather than through your PC speaker (even if you have one).
pcrate=22050	11025, 22050, 44100	Sample rate of the PC-Speaker sound generation. Setting this higher than 22050 will slow emulation down and will sound significantly different from a real PC speaker.
tandy=auto	on, off, auto	Tandy Sound System emulation. When set to auto, emulation is present only if the emulated system is set to tandy.
tandyrate=22050	11025, 22050, 44100	Sample rate of the Tandy 3-Voice generation.
disney=true	true, false	Disney Sound Source emulation. Disable this unless you have a game that requires it.

[edit] Joystick

setting=default	choices	explanation
joysticktype=auto	<type>	Type of joystick to emulate: auto : determines emulation type depending on what the real joystick is none: no joystick emulation. 2axis: basic controller; supports two joysticks 4axis: basic controller fcs (Thrustmaster) ch (CH Flightstick).
timed=true	true, false	enable timed intervals for axes (false is old style behaviour).
autofire=false	true, false	fires rapidly for as long as you keep the button pressed. Useful in games that treat holding down the button as only firing shots at a certain speed, but put no limits on how many shots you can fire by rapidly tapping the button. Some games (such as Duke Nukem) use weapon upgrades to increase the held-button firing rate; these upgrades can be bypassed by using this setting.
swap34=false	true, false	swap the 3rd and 4th axis. Useful for certain joysticks, useless for others.
buttonwrap=true	true, false	enable button wrapping at the number of emulated buttons.

[edit] Serial

serial1-4: set type of device connected to com port.

Can be disabled, dummy, modem, nullmodem, directserial.

Additional parameters must be in the same line in the form of parameter:value. Parameter for all types is irq.

• for directserial: realport (required), rxdelay (optional).
• for modem: listenport (optional).
• for nullmodem: server, rxdelay, txdelay, telnet, usedtr, transparent, port, inhsocket (all optional).

Example: serial1=modem listenport:5000

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[edit] DOS

setting=default	choices	explanation
xms=true	true, false	Enable XMS support.
ems=true	true, false	Enable EMS support.
umb=true	true, false	Enable UMB support.
keyboardlayout=none	<langcode>	Language code of the keyboard layout (or none for US 101 key).

This section is a stub. Help us expand it, and you get a cookie.

[edit] IPX

setting=default	choices	explanation
ipx=false	true, false	Enable IPX over UDP/IP emulation.

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[edit] autoexec

Lines placed here will run at startup. In addition to autoexec commands recognised by MS-DOS you can also use some special commands that only DOSBox recognises.

[edit] Mounting a virtual hard drive

For a virtual hard drive, simply create a folder on your physical hard drive (you could mount the root directory of your hard drive but this is not recommended). You can call this folder whatever you like, and it doesn't even have to have an 8.3 file name. Add the drive mount in the following manner:

mount C C:\Games

In this example, DOSBox will treat C:\Games as the C:\ root of the emulated hard drive. You can manipulate the files in this directory both through your operating system and also from within DOSBox itself.

[edit] Mounting an optical drive

If you want DOSBox to be able to access your optical drive, use the following:

mount D D:\ -t cdrom

In this example, a physical optical drive assigned to the letter D:\ is treated by DOSBox as a CD-ROM drive assigned to the letter D. If your optical drive has a different letter simply change the second instance of the drive letter. You can also use this method to treat a folder on your hard drive as the emulated CD-ROM drive.

[edit] Starting drive letter

By default, DOSBox starts in the Z: drive. Since some applications will only run from a drive with the letter C:, unless you have a particular reason for using the Z: drive you will want to set a different letter as the default.

To do so, simply add the following on its own line:

C:

This will make DOSBox launch in the emulated C: drive rather than the Z: drive. If you have mounted your virtual drive with a different letter, or want DOSBox to start in a different letter, change this line appropriately.

[edit] Other commands

Users with a non-English keyboard layout may want to use their local layout. This is done by the "keyb" command with the country code. For German layout, it would be:

keyb gr

On some games, the American keyboard layout is assumed so their setting can't be overwritten by this.

At Mac OS X systems, the keyb.com of DosBox is said to crash GEOS. There are other keyb files available that are not officially supported where this doesn't occur.