Core commands

-help, -?

Displays current MESS version and copyright notice.

-validate, -valid

Performs internal validation on every driver in MESS. Run this before submitting changes to ensure that you haven't violated any of the core system rules.

Configuration commands

-createconfig, -cc

Creates the default mess.ini file in the current directory. All the configuration options (not commands) described below can be permanently changed by editing this configuration file.

-showconfig, -sc

Displays the current configuration settings.

-showusage, -su

Displays a summary of all the command line options. For options that are not mentioned here, the short summary given by -showusage is usually sufficient.

Frontend commands

-listxml, -lx [system|wildcard]

List comprehensive details for all of the supported systems. The output is quite long, so it is usually better to redirect this into a file. The output is in XML format. By default all systems are listed; however, you can limit this list by specifying a driver name or wildcard after the -listxml command.

-listfull, -ll [system|wildcard]

Displays a list of system driver names and descriptions. By default all systems are listed; however, you can limit this list by specifying a driver name or wildcard after the -listfull command.

-listsource, -ls [system|wildcard]

Displays a list of drivers and the names of the source files their system drivers live in. Useful for finding which driver a system runs on in order to fix bugs. By default all systems are listed; however, you can limit this list by specifying a driver name or wildcard after the -listsource command.

-listclones, -lc [system|wildcard]

Displays a list of clones. By default all clones are listed; however, you can limit this list by specifying a driver name or wildcard after the -listclones command.

-listbrothers, -lb [system|wildcard]

Displays a list of "brothers" or other drivers from same sourcefile. By default all systems are listed; however, you can limit this list by specifying a driver name or wildcard after the -listbrothers command.

-listcrc

Displays a full list of CRCs of all ROM images referenced by all drivers within MESS code.

-listroms, -lr system

Displays a list of ROM images referenced by the specified system.

-listsamples system

Displays a list of samples referenced by the specified system.

-verifyroms [system|wildcard]

Checks for invalid or missing ROM images. By default all drivers that have valid ZIP files or directories in the rom path are verified; however, you can limit this list by specifying a driver name or wildcard after the -verifyroms command.

-verifysamples [system|wildcard]

Checks for invalid or missing samples. By default all drivers that have valid ZIP files or directories in the samplepath are verified; however, you can limit this list by specifying a driver name or wildcard after the -verifyroms command.

-romident

Attempts to identify ROM files, if they are known to MESS, in the specified .zip file or directory. This command can be used to try and identify ROM sets taken from unknown boards. On exit, the errorlevel is returned as one of the following:
0 all files were identified
7 all files were identified except for some "non-ROM" files
8 some files were identified
9 no files were identified

-listdevices, -ld

Output the list of devices referenced by a given system or set of systems.

-listslots, -lslot

Output the list of available slots and slot devices for the system.

-listmedia, -lm

Output the list of available media for the system.

-listsoftware, -lsoft

Output the list of known software for the system.

-verifysoftware, -vsoft [gamename|wildcard]

Checks for invalid or missing ROM images in your software lists. By default all drivers that have valid ZIP files or directories in the rompath are verified; however, you can limit this list by specifying a specific driver name or wildcard.

-getsoftlist, -glist

Retrieve software list by name.

-verifysoftlist, -vlist [softwarelistname]

Checks a specified software list for missing ROM images if files exist for issued softwarelistname. By default, all drivers that have valid ZIP files or directories in the rompath are verified; however, you can limit this list by specifying a specific softwarelistname (without .XML).

-listmidi, -mlist

List available MIDI I/O devices.

-listnetwork, -nlist

List available network adapters.

Configuration options

-[no]readconfig, -[no]rc

Enables or disables the reading of the config files. When enabled (which is the default), MESS reads the following config files in order:
1. mess.ini
the main configuration file
2. [driver].ini
based on the source file name of the system driver
3. debug.ini, if the debugger is enabled
4. vector.ini, for vector games only
5. [driver].ini
based on the source filename of the game driver
6. [parent].ini
for clones only, may be called recursively
4. [system].ini
note this sometimes resolves to the same of the source driver

The settings in the later ini's override those in the earlier ini's. The default is ON (-readconfig).

-[no]writeconfig, -[no]wc

Write configuration to [driver].ini on exit. Default is OFF (-nowriteconfig).

Search path options

-rompath, -rp, -biospath, -bp pathname

Specifies a list of paths within which to find ROM or hard disk images. Multiple paths can be specified by separating them with semicolons. The default is 'roms' (that is, a directory 'roms' in the same directory as the MESS executable).

-hashpath pathname

Specifies a list of paths within which to search for software hash files. Multiple paths can be specified by separating them with semicolons. The default is 'hash' (that is, a directory 'hash' in the same directory as the MESS executable).

-samplepath, -sp pathname

Specifies a list of paths within which to find sample files. Multiple paths can be specified by separating them with semicolons. The default is 'samples' (that is, a directory 'samples' in the same directory as the MESS executable).

-artpath, -artwork_directory pathname

Specifies a list of paths within which to find artwork files. Multiple paths can be specified by separating them with semicolons. The default is 'artwork' (that is, a directory 'artwork' in the same directory as the MESS executable).

-ctrlrpath, -ctrlr_directory pathname

Specifies a list of paths within which to find controller-specific configuration files. Multiple paths can be specified by separating them with semicolons. The default is 'ctrlr' (that is, a directory 'ctrlr' in the same directory as the MESS executable).

-inipath pathname

Specifies a list of paths within which to find .ini files. Multiple paths can be specified by separating them with semicolons. The default is '/etc/mess'.

-fontpath pathname

Specifies a list of paths within which to find .bdf font files. Multiple paths can be specified by separating them with semicolons. The default is '.' (that is, search in the same directory as the MESS executable).

-cheatpath pathname

Specifies a list of paths within which to find cheat files. Multiple paths can be specified by separating them with semicolons. The default is 'cheat' (that is, a directory 'cheat' in the same directory as the MESS executable).

-crosshairpath pathname

Specifies a list of paths within which to find crosshair files. Multiple paths can be specified by separating them with semicolons. The default is 'crosshair' (that is, a directory 'crosshair' in the same directory as the MESS executable). If the Crosshair is set to default in the menu, MESS will look for system/cross#.png and then cross#.png in the specified path, where # is the player number. Failing that, MESS will use built-in default crosshairs.

-pluginspath pathname

Specifies a single path within which to find plugins. The default is 'plugins' (that is, a directory 'plugins' in the same directory as the MESS executable).

-languagepath pathname

Specifies a single path within which to find language files. The default is 'language' (that is, a directory 'language' in the same directory as the MESS executable).

Output Directory Options

-cfg_directory pathname

Specifies a single directory where configuration files are stored. Configuration files store user configurable settings that are read at startup and written when MESS exits. The default is 'cfg' (that is, a directory 'cfg' in the same directory as the MESS executable). If this directory does not exist, it will be automatically created.

-nvram_directory pathname

Specifies a single directory where NVRAM files are stored. NVRAM files store the contents of EEPROM and non-volatile RAM (NVRAM) for systems which used this type of hardware. This data is read at startup and written when MESS exits. The default is 'nvram' (that is, a directory 'nvram' in the same directory as the MESS executable). If this directory does not exist, it will be automatically created.

-input_directory pathname

Specifies a single directory where input recording files are stored. Input recordings are created via the -record option and played back via the -playback option. The default is 'inp' (that is, a directory 'inp' in the same directory as the MESS executable). If this directory does not exist, it will be automatically created.

-state_directory pathname

Specifies a single directory where save state files are stored. Save state files are read and written either upon user request, or when using the -autosave option. The default is 'sta' (that is, a directory 'sta' in the same directory as the MESS executable). If this directory does not exist, it will be automatically created.

-snapshot_directory pathname

Specifies a single directory where screen snapshots are stored, when requested by the user. The default is 'snap' (that is, a directory 'snap' in the same directory as the MESS executable). If this directory does not exist, it will be automatically created.

-diff_directory pathname

Specifies a single directory where hard drive differencing files are stored. Hard drive differencing files store any data that is written back to a hard disk image, in order to preserve the original image. The differencing files are created at startup when a system with a hard disk image. The default is 'diff' (that is, a directory 'diff' in the same directory as the MESS executable). If this directory does not exist, it will be automatically created.

-comment_directory pathname

Specifies a single directory where debugger comment files are stored. Debugger comment files are written by the debugger when comments are added to the disassembly for a system. The default is 'comments' (that is, a directory 'comments' in the same directory as the MESS executable). If this directory does not exist, it will be automatically created.

State/playback options

-state slot

Immediately after starting the specified system, will cause the save state in the specified slot to be loaded.

-[no]autosave

When enabled, automatically creates a save state file when exiting MESS and automatically attempts to reload it when later starting MESS with the same system. This only works for systems that have explicitly enabled save state support in their driver. The default is OFF (-noautosave).

-playback, -pb filename

Specifies a file from which to play back a series of system inputs. This feature does not work reliably for all systems, but can be used to watch a previously recorded system session from start to finish. In order to make things consistent, you should only record and playback with all configuration (.cfg), NVRAM (.nv), and memory card files deleted. The default is NULL (no playback).

-[no]exit_after_playback

If play back is enabled (see -playback option) the program exits when end of file is reached. Otherwise the machine will continue to run. Default is OFF (-noexit_after_playback).

-record, -rec filename

Specifies a file to record all input from a system session. This can be used to record a system session for later playback. This feature does not work reliably for all systems, but can be used to watch a previously recorded system session from start to finish. In order to make things consistent, you should only record and playback with all configuration (.cfg), NVRAM (.nv), and memory card files deleted. The default is NULL (no recording).

-[no]record_timecode

Specify whether to create a timecode file. It contains a line with elapsed times on each press of timecode shortcut key (default is F12). This option works only when recording mode is enabled (-record option). The file is saved on inp folder. Default is OFF (-norecord_timecode).

-mngwrite filename

Writes each video frame to the given file in MNG format, producing an animation of the system session. Note that -mngwrite only writes video frames; it does not save any audio data. Use -wavwrite for that, and reassemble the audio/video using offline tools. The default is NULL (no recording).

-aviwrite filename

Stream video and sound data to the given file in AVI format, producing an animation of the system session complete with sound. The default is NULL (no recording).

-wavwrite filename

Writes the final mixer output to the given file in WAV format, producing an audio recording of the system session. The default is NULL (no recording).

-snapname string

Describes how MESS should name files for snapshots. string provides a template that is used to generate a filename. Three simple substitutions are provided: the / character represents the path separator on any target platform (even Windows); the literal %g represents the driver name of the current system; and the literal %i represents an incrementing index. If %i is omitted, then each snapshot taken will overwrite the previous one; otherwise, MESS will find the next empty value for %i and use that for a filename. The default is %g/%i, which creates a separate folder for each system, and names the snapshots under it starting with 0000 and increasing from there. In addition to the above, for drivers using different media, like carts or floppy disks, you can also use the %d_[media] indicator. Replace [media] with the media switch you want to use. A few examples: if you use mess nes -cart robby -snapname %g/%d_cart snapshots will be saved as snaps/nes/robby.png; if you use mess c64 -flop1 robby -snapname %g/%d_flop1/%i snapshots will be saved as snaps/c64/robby/0000.png.

-snapsize widthxheight

Hard-codes the size for snapshots and movie recording. By default, MESS will create snapshots at the system's current resolution in raw pixels, and will create movies at the system's starting resolution in raw pixels. If you specify this option, then MESS will create both snapshots and movies at the size specified, and will bilinear filter the result. Note that this size does not automatically rotate if the system is vertically oriented. The default is 'auto'.

-snapview internal|auto|viewname

Specifies the view to use when rendering snapshots and movies. By default, both use a special 'internal' view, which renders a separate snapshot per screen or renders movies only of the first screen. By specifying this option, you can override this default behavior and select a single view that will apply to all snapshots and movies. Note that viewname does not need to be a perfect match; rather, it will select the first view whose name matches all the characters specified by viewname. For example, -snapview native will match the "Native (15:14)" view even though it is not a perfect match. viewname can also be 'auto', which selects the first view with all screens present. The default value is 'internal'.

-[no]snapbilinear

Specify whether snapshot/movie should have bilinear filtering applied. Default is ON (-snapbilinear).

-statename string

Describes how MESS should store save state files, relative to the state_directory path. string provides a template that is used to generate a relative path. Two simple substitutions are provided: the / character represents the path separator on any target platform (even Windows); the literal %g represents the driver name of the current game. The default is '%g', which creates a separate folder for each game. In addition to the above, for drivers using different media, like carts or floppy disks, you can also use the %d_[media] indicator. Replace [media] with the media switch you want to use. A few examples: if you use mess nes -cart robby -statename %g/%d_cart save states will be stored inside sta/nes/robby/; if you use mess c64 -flop1 robby -statename %g/%d_flop1 save states will be stored inside sta/c64/robby/.

-[no]burnin

Tracks brightness of the screen during play and at the end of emulation generates a PNG that can be used to simulate burn-in effects on other systems. The resulting PNG is created such that the least-used areas of the screen are fully white (since burned-in areas are darker, all other areas of the screen must be lightened a touch). The intention is that this PNG can be loaded via an artwork file with a low alpha (e.g, 0.1-0.2 seems to work well) and blended over the entire screen. The PNG files are saved in the snap directory under the system/burnin-<screen.name>.png. The default is OFF (-noburnin).

Performance options

-[no]autoframeskip, -[no]afs

Automatically determines the frameskip level while you're playing the system, adjusting it constantly in a frantic attempt to keep the system running at full speed. Turning this on overrides the value you have set for -frameskip below. The default is OFF (-noautoframeskip).

-frameskip, -fs value

Specifies the frameskip value (autoframeskip must be disabled). This is the number of frames out of every 12 to drop when running. For example, if you say -frameskip 2, then MESS will display 10 out of every 12 frames. By skipping those frames, you may be able to get full speed in a system that requires more horsepower than your computer has. The default value is 0, which skips no frames.

-seconds_to_run, -str value

This option can be used for benchmarking and automated testing. It tells MESS to stop execution after a fixed number of seconds. By combining this with a fixed set of other command line options, you can set up a consistent environment for benchmarking MESS performance. In addition, upon exit, the -str option will write a screenshot called final.png to the system's snapshot directory.

-[no]throttle

Configures the default thottling setting. When throttling is on, MESS attempts to keep the system running at the system's intended speed. When throttling is off, MESS runs the system as fast as it can. Note that the fastest speed is more often than not limited by your graphics card, especially for older systems. The default is ON (-throttle).

-[no]sleep

Allows MESS to give time back to the system when running with -throttle. This allows other programs to have some CPU time, assuming that the system isn't taxing 100% of your CPU resources. This option can potentially cause hiccups in performance if other demanding programs are running. The default is ON (-sleep).

-speed value

Controls the speed of gameplay, relative to realtime; smaller numbers are slower. Default is 1.00.

-[no]refreshspeed, -[no]rs

Automatically adjusts the -speed parameter to keep the effective refresh rate below that of the lowest screen refresh rate. Default is OFF (-norefreshspeed).

-numprocessors, -np value

Set number of processors; this overrides the number the system reports.

-bench value

Benchmark for the given number of emulated seconds; implies -video none -sound none -nothrottle.

-[no]sdlvideofps

Show SDL video performance. Default is OFF (-nosdlvideofps).

Rotation options

-[no]rotate

Rotate the system to match its normal state (horizontal/vertical). This ensures that both vertically and horizontally oriented systems show up correctly without the need to rotate your monitor. If you want to keep the system displaying 'raw' on the screen the way the actual machine would have, turn this option off. The default is ON (-rotate).

-[no]ror -[no]rol

Rotate the system screen to the right (clockwise) or left (counter-clockwise) relative to either its normal state (if -rotate is specified) or its native state (if -norotate is specified). Default for both is OFF (-noror -norol).

-[no]autoror -[no]autorol

These options are designed for use with pivoting screens that only pivot in a single direction. If your screen only pivots clockwise, use -autorol to ensure that the system will fill the screen either horizontally or vertically in one of the directions you can handle. If your screen only pivots counter-clockwise, use -autoror. Default for both is OFF (-noautoror -noautorol).

-[no]flipx -[no]flipy

Flip (mirror) the system screen either horizontally (-flipx) or vertically (-flipy). The flips are applied after the -rotate and -ror/-rol options are applied. Default for both is OFF (-noflipx -noflipy).

Artwork options

-[no]artwork_crop, -[no]artcrop

Enable cropping of artwork to the system screen area only. This option can also be controlled via the Video Options menu in the user interface. The default is OFF (-noartwork_crop).

-[no]use_backdrops, -[no]backdrop

Enables/disables the display of backdrops. The default is ON (-use_backdrops).

-[no]use_overlays, -[no]overlay

Enables/disables the display of overlays. The default is ON (-use_overlays).

-[no]use_bezels, -[no]bezel

Enables/disables the display of bezels. The default is ON (-use_bezels).

-[no]use_cpanels, -[no]cpanel

Enables/disables the display of cpanels. The default is ON (-use_bezels).

-[no]use_marquees, -[no]marquee

Enables/disables the display of marquees. The default is ON (-use_bezels).

Screen options

-brightness value

Controls the default brightness, or black level, of the system screens. This option does not affect the artwork or other parts of the display. Using the MESS UI, you can individually set the brightness for each system screen; this option controls the initial value for all visible system screens. The standard value is 1.0. Selecting lower values (down to 0.1) will produce a darkened display, while selecting higher values (up to 2.0) will give a brighter display. The default is 1.0.

-contrast value

Controls the contrast, or white level, of the system screens. This option does not affect the artwork or other parts of the display. Using the MESS UI, you can individually set the contrast for each system screen; this option controls the initial value for all visible system screens. The standard value is 1.0. Selecting lower values (down to 0.1) will produce a dimmer display, while selecting higher values (up to 2.0) will give a more saturated display. The default is 1.0.

-gamma value

Controls the gamma, which produces a potentially nonlinear black to white ramp, for the system screens. This option does not affect the artwork or other parts of the display. Using the MESS UI, you can individually set the gamma for each system screen; this option controls the initial value for all visible system screens. The standard value is 1.0, which gives a linear ramp from black to white. Selecting lower values (down to 0.1) will increase the nonlinearity toward black, while selecting higher values (up to 3.0) will push the nonlinearity toward white. The default is 1.0.

-pause_brightness value

This controls the brightness level when MESS is paused. The default value is 0.65.

-effect [none|filename[.png]]

Name of a PNG file to use for visual effects, or 'none'. Default is 'none'.

Vector rendering options

-beam_width_min value

-beam_width_max value

Sets the minimum and maximum width of the vectors. This is a scaling factor against the standard vector width, which is interpolated between minimum and maximum according to the beam's intensity. A value of 1.0 will keep the default vector line width. Smaller values will reduce the width, and larger values will increase the width. The default is 1.0.

-beam_intensity_weight value

Applies an exponential weight to the minimum and maximum beam width. For positive values the interpolated scaling factor will affect lines with higher intensity more than lines with lower intensity. The default is 0.0.

-flicker value

Simulates a vector "flicker" effect, similar to a vector monitor that needs adjustment. This option requires a float argument in the range of 0.00-100.00 (0=none, 100=maximum). The default is 0.

Video options

-video [soft|opengl|bgfx|none]

Specifies which video subsystem to use for drawing:
soft uses software rendering, which is slower but more compatible.
opengl uses OpenGL and your graphics accelerator to speed up many aspects of drawing MAME including compositing artwork, overlays, and bezels, as well as stretching the image to fit your screen.
bgfx uses the bgfx renderer which supports portable shaders and multiple graphics APIs including OpenGL, OpenGL ES and DirectX.
none does no drawing and is intended for CPU benchmarking.
Default is 'soft' on Linux or 'opengl' on macOS.

-numscreens [1-4]

Number of screens to create; usually, you want just one. Default is '1'.

-[no]window, -[no]w

Run MESS in either full screen or a window. This is a fully-featured window mode where the window resizes as necessary to track what the system does. And you can resize it yourself with your OS's standard window controls. The default is OFF (-nowindow).

-[no]maximize, -[no]max

Controls initial window size in windowed mode. If it is set on, the window will initially be set to the maximum supported size when you start MESS. If it is turned off, the window will start out at the smallest supported size. This option only has an effect when the -window option is used. The default is ON (-maximize).

-[no]keepaspect, -[no]ka

Forces the correct aspect ratio. This means when you're resizing the window in windowed mode the actual system image will resize in discrete steps to maintain the proper shape of the system graphics. If you turn this off you can resize the window to anything you like and get funny squishing and stretching. The same applies for full-screen. Default is ON (-keepaspect).

-[no]unevenstretch, -[no]ues

Allow non-integer stretch factors. Video purists should stay far, far away from this option, while everyone else will be happy to know that it lets you fill the screen properly in full-screen mode. Default is ON (-unevenstretch).

-[no]unevenstretchx, -[no]uesx

Act as -[no]unevenstretch on horizontal basis only.

-[no]intoverscan, -[no]ios

Allow overscan on integer scaled targets.

-intscalex, -sx

Set horizontal integer scale factor.

-intscaley, -sy

Set vertical integer scale factor.

-[no]centerh

Center horizontally within the view area. Default is ON (-centerh).

-[no]centerv

Center vertically within the view area. Default is ON (-centerv).

-[no]waitvsync, -[no]vs

Enable waiting for the start of VBLANK before flipping screens; reduces tearing effects. Default is OFF (-nowaitvsync).

-[no]syncrefresh, -[no]srf

Enable using the start of VBLANK for throttling instead of the game time. Default is OFF (-nosyncrefresh).

Software video rendering subsystem options

-prescale [value]

Scale screen rendering by this amount in software. Default is 1.

-scalemode, -sm [none|async|yv12|yuy2|yv12x2|yuy2x2]

Hardware scaling mode.
none use software rendering.
async async overlay.
yv12 yv12 overlay.
yuy2 yuy2 overlay.
yv12x2 yv12 overlay using x2 prescaling.
yuy2x2 yuy2 overlay using x2 prescaling.
Default is NONE.

OpenGL video rendering subsystem options

-[no]filter, -[no]glfilter, -[no]flt

Enable bilinear filtering on screen output. Default is ON (-filter).

-prescale [value]

Scale screen rendering by this amount in software. Default is 1.

-[no]gl_forcepow2texture

Force power of two textures. Default is OFF (-nogl_forcepow2texture).

-[no]gl_notexturerect

Don't use OpenGL GL_ARB_texture_rectangle. Turn off if corruption occurs in OpenGL mode, at cost of some performance loss. Default is ON (-gl_notexturerect).

-[no]gl_vbo

Enable OpenGL VBO, if available, for a performance increase. Turn off if corruption occurs. Default is ON (-gl_vbo).

-[no]gl_pbo

Enable OpenGL PBO, if available, for a performance increase. Turn off if corruption occurs. Default is ON (-gl_pbo).

-[no]gl_glsl

Enable OpenGL GLSL, if available, for a performance increase. Default is OFF (-nogl_glsl).

-gl_glsl_filter value

Enable OpenGL GLSL filtering instead of FF filtering 0=plain, 1=bilinear. Default is 1: bilinear.

-glsl_shader_mame[0-9]

Preferred custom OpenGL GLSL shader set mame bitmap (from 0 to 9).

-glsl_shader_screen[0-9]

Preferred custom OpenGL GLSL shader screen bitmap (from 0 to 9).

-gl_glsl_vid_attr

Enable OpenGL GLSL handling of brightness and contrast. Better RGB system performance for free. Default is ON.

-screen

Explicit name for all screens; 'auto' here will try to make a best guess.

-aspect, -screen_aspect

Aspect ratio for all screens; 'auto' here will try to make a best guess.

-resolution, -r

Preferred resolution for all screens; format is widthxheight[@refreshrate] or 'auto'.

-view

Preferred view for all screens

-screen[0-3]

Explicit name of the first|second|third|fourth screen; 'auto' here will try to make a best guess.

-aspect[0-3]

Aspect ratio of the first|second|third|fourth screen; 'auto' here will try to make a best guess.

-resolution[0-3], -r[0-3]

Preferred resolution for the first|second|third|fourth screen; format is widthxheight[@refreshrate] or 'auto'.

-view[0-3]

Preferred view for the first|second|third|fourth screen.

BGFX post-processing options

-bgfx_path pathname

This is where your BGFX shader files are stored. The default is 'bgfx' (that is, a directory "bgfx" in the same directory as the MESS executable).

-bgfx_backend auto|opengl

Selects a rendering backend for BGFX to use. The default is 'auto', which will let MESS choose the best selection for you.

-bgfx_debug

Enables BGFX debugging features. Most users will not need to use this.

-bgfx_screen_chains default|unfiltered|hlsl[,...]

This dictates how to handle BGFX rendering on a per-display basis. For each display specify one of the possible choices:
default default bilinear filterered output
unfiltered nearest neighbor unfiltered output
hlsl HLSL display simulation through shaders
Separate directives for each window with a comma (,) and for each physical screen with a colon (:). For example, for an emulated game with 3 displays emulated on 3 windows on your monitor, -bgfx_screen_chains default,unfiltered,default specifies to apply default filter on what is been rendered on the first and third window and leave the content of the second window unfiltered.

-bgfx_shadow_mask filename

This specifies the shadow mask effect PNG file. Default is 'slot-mask.png'.

-bgfx_avi_name filename

This specifies a filename for BGFX output logging.

Full screen options

-[no]switchres

Affects full screen mode only. Chooses if MESS can try to change the screen resolution (color depth is normally left alone) when in full-screen mode. If it's off, you always get your desktop resolution in full-screen mode (which can be useful for LCDs). Default is OFF (-noswitchres).

-[no]useallheads

Split full screen image across monitors. Default is OFF (-nouseallhead).

Sound options

-sound [sdl|portaudio|coreaudio|dsound|xaudio2|none]

Specifies which sound subsystem to use for audio output:
sdl uses the Simple DirectMedia Layer audio output system (not available on Windows by default).
portaudio uses the PortAudio library which supports low-latency output and multiple audio APIs.
coreaudio uses the Core Audio API which supports low-latency output and AudioUnit effects (only available on macOS).
dsound uses the DirectSound API (only available on Windows).
xaudio2 uses the XAudio2 API which supports low-latency output (only available on Windows).
none produces no audio output.
Default is 'dsound' on Windows, 'coreaudio' on macOS or 'sdl' on other platforms.

-samplerate, -sr value

Sets the audio sample rate. Smaller values (e.g. 11025) cause lower audio quality but faster emulation speed. Higher values (e.g. 48000) cause higher audio quality but slower emulation speed. The default is 48000.

-[no]samples

Use samples if available. The default is ON (-samples).

-volume, -vol value

Sets the startup volume. It can later be changed with the user interface (see Keys section). The volume is an attenuation in dB: for example, '-volume -12' will start with -12dB attenuation. The default is 0.

-audio_latency value

This controls the amount of latency built into the audio streaming. The exact behavior depends on the selected audio output module (see the -sound option). Smaller values provide less audio delay while requiring better system performance. Higher values increase audio delay but may help avoid buffer under-runs and audio interruptions. The default is 1.

Input options

-[no]coin_lockout, -[no]coinlock

Enables simulation of the "coin lockout" feature that is implemented on a number of arcade game PCBs. It was up to the operator whether or not the coin lockout outputs were actually connected to the coin mechanisms. If this feature is enabled, then attempts to enter a coin while the lockout is active will fail and will display a popup message in the user interface. If this feature is disabled, the coin lockout signal will be ignored. The default is ON (-coin_lockout).

-ctrlr controller

Enables support for special controllers. Configuration files are loaded from the ctrlrpath. They are in the same format as the .cfg files that are saved, but only control configuration data is read from the file. The default is NULL (no controller file).

-[no]mouse

Controls whether or not MESS looks for a mouse controller to use. Note that in many cases, lightguns are treated as mice by the operating system, so you may need to enable this to enable lightgun support. When this is enabled, you will not be able to use your mouse while running MESS. If you want to get control of your computer back, you will need to either pause MESS or quit. The default is OFF (-nomouse).

-[no]joystick, -[no]joy

Controls whether or not MESS looks for joystick/gamepad controllers. The default is ON (-joystick).

-[no]lightgun, -[no]gun

Controls whether or not MESS makes use of lightgun controllers. Note that most lightguns map to the mouse, so using -lightgun and -mouse together may produce strange results. The default is OFF (-nolightgun).

-[no]multikeyboard, -[no]multikey

Determines whether MESS differentiates between multiple keyboards. Some systems may report more than one keyboard; by default, the data from all of these keyboards is combined so that it looks like a single keyboard. Turning this option on will enable MESS to report keypresses on different keyboards independently. The default is OFF (-nomultikeyboard).

-[no]multimouse

Determines whether MESS differentiates between multiple mice. Some systems may report more than one mouse device; by default, the data from all of these mice is combined so that it looks like a single mouse. Turning this option on will enable MESS to report mouse movement and button presses on different mice independently. The default is OFF (-nomultimouse).

-[no]steadykey, -[no]steady

Some systems require two or more buttons to be pressed at exactly the same time to make special moves. Due to limitations in the PC keyboard hardware, it can be difficult or even impossible to accomplish that using the standard keyboard handling. This option selects a different handling that makes it easier to register simultaneous button presses, but has the disadvantage of making controls less responsive. The default is OFF (-nosteadykey).

-[no]ui_active

Enable MESS user interface on top of emulated keyboard (if present). User interface may be toggled during execution by pressing the key defined with -ui_modekey. Default is OFF (-noui_active).

-[no]offscreen_reload, -[no]reload

Controls whether or not MESS treats a second button input from a lightgun as a reload signal. In this case, MESS will report the gun's position as (0,MAX) with the trigger held, which is equivalent to an offscreen reload. This is only needed for systems that required you to shoot offscreen to reload, and then only if your gun does not support off screen reloads. The default is OFF (-nooffscreen_reload).

-joystick_map, -joymap map

Controls how joystick values map to digital joystick controls. See /usr/share/doc/mame-common/config.txt for full details on joymap format.

-joystick_deadzone, -joy_deadzone, -jdz value

If you play with an analog joystick, the center can drift a little. joystick_deadzone tells how far along an axis you must move before the axis starts to change. This option expects a float in the range of 0.0 to 1.0. Where 0 is the center of the joystick and 1 is the outer limit. The default is 0.3.

-joystick_saturation, -joy_saturation, -jsat value

If you play with an analog joystick, the ends can drift a little, and may not match in the +/- directions. joystick_saturation tells how far along an axis movement change will be accepted before it reaches the maximum range. This option expects a float in the range of 0.0 to 1.0, where 0 is the center of the joystick and 1 is the outer limit. The default is 0.85.

-[no]natural, -[no]nat

Allows user to specify whether or not to use a natural keyboard. This allows you to start your game or system in a 'native' mode, depending on your region, allowing compatibility for non-"QWERTY" style keyboards. The default is OFF (-nonatural).

-[no]joystick_contradictory, -[no]joy_contradictory

Enable contradictory direction digital joystick input at the same time. Default is OFF (-nojoystick_contradictory).

-uimodekey, -umk value

Specifies the key used to toggle between full and partial UI mode.

-uifontprovider auto|sdl|none

Provider for ui font.

-output console|network|none

Provider for output.

-keyboardprovider auto|sdl|none

Provider for keyboard input.

-mouseprovider auto|sdl|none

Provider for mouse input.

-lightgunprovider auto|none

Provider for lightgun input.

-joystickprovider auto|sdl|none

Provider for joystick input.

-[no]keymap

Enable keymap for non-QWERTY keyboards. Used in conjunction with -keymap_file. Default is OFF (-nokeymap).

-keymap_file keymap_file

Specifies the full path to the keymap file to be used. A few keymap files are available in /usr/share/games/mess/keymaps.

-joy_idx[0-8] joystick

With these options you can assign a joystick to a specific index in MESS. Even if the kernel will list the joysticks in a different order on the next boot, MESS will still see the joystick as e.g. "Joystick 2". Use mame -v to see which joysticks are recognized. Default is 'auto'.

-[no]sixaxis

Use special handling for PS3 Sixaxis controllers. Default is OFF (-nosixaxis).

-lightgun_index[1-8]

Map lightgun to specific index in MESS.

-videodriver, -vd x11|directfb|auto

SDL video driver to use; auto selects SDL default.

-audiodriver, -ad alsa|arts|auto

SDL audio driver to use; auto selects SDL default.

-gl_lib alsa|arts|auto

Alternative libGL.so to use; auto selects SDL default.

Input automatic enable options

-paddle_device, -paddle [none|keyboard|mouse|lightgun|joystick]

-adstick_device, -adstick [none|keyboard|mouse|lightgun|joystick]

-pedal_device, -pedal [none|keyboard|mouse|lightgun|joystick]

-dial_device, -dial [none|keyboard|mouse|lightgun|joystick]

-trackball_device, -trackball [none|keyboard|mouse|lightgun|joystick]

-lightgun_device [none|keyboard|mouse|lightgun|joystick]

-positional_device [none|keyboard|mouse|lightgun|joystick]

-mouse_device [none|keyboard|mouse|lightgun|joystick]

Each of these options controls automatically enabling the mouse, or joystick depending on the presence of a particular class of analog control for a particular system. For example, if you specify the option -paddle mouse, then any system that has a paddle control will automatically enable mouse controls just as if you had explicitly specified -mouse. Note that these controls override the values of -[no]mouse, -[no]joystick, etc.

Debugging options

-[no]log

Creates a file called error.log which contains all of the internal log messages generated by the MESS core and system drivers. The default is OFF (-nolog).

-[no]verbose, -[no]v

Displays internal diagnostic information. This information is very useful for debugging problems with your configuration. Please use the -verbose option and include the resulting information when reporting bugs. The default is OFF (-noverbose).

-[no]update_in_pause

Enables updating the screen bitmap while the system is paused. This is useful for debuggin in some scenarios (and gets in the way in others). Default is OFF (-noupdate_in_pause).

-[no]debug, -[no]d

Activates the integrated debugger. By default, the debugger is entered by pressing the tilde (~) key during emulation. It is also entered immediately at startup. The default is OFF (-nodebug).

-debugscript filename

Specifies a file that contains a list of debugger commands to execute immediately upon startup. The default is NULL (no commands).

-debugger debugger_name

Name of the debugger to use. Default is AUTO.

-debugger_font, -dfont font_name

Specifies the font to use for debugging. Default is AUTO.

-debugger_font_size, -dfontsize size

Specifies the font size to use for debugging.

-[no]oslog

Outputs the error.log data to the system debugger. This can be used at the same time as -log to output the log data to both targets as well. Default is OFF (-nooslog).

Misc options

-[no]drc

Enable DRC cpu core if available. Default is ON (-drc).

-[no]drc_use_c

Force DRC use C backend. Default is OFF (-nodrc_use_c).

-[no]drc_log_uml

Write DRC UML disassembly log. Default is OFF (-nodrc_log_uml).

-[no]drc_log_native

Write DRC native disassembly log. Default is OFF (-no_drc_log_native).

-bios biosname

Specifies the specific BIOS to use with the current system, for systems that make use of a BIOS. The -listxml output will list all of the possible BIOS names for a system. The default is 'default'.

-[no]cheat, -[no]c

Activates the cheat menu with autofire options and other tricks from the cheat database, if present. The default is OFF (-nocheat).

-[no]skip_gameinfo

Forces MESS to skip displaying the system info screen. The default is OFF (-noskip_gameinfo).

-uifont fontname

Specifies the name of a BDF font file to use for the UI font. If this font cannot be found or cannot be loaded, the system will fall back to its built-in UI font. On some platforms fontname can be a system font name instead of a BDF font file. The default is 'default' (use the OSD-determined default font).

-ui simple|cabinet

Type of UI.

-ramsize, -ram value

Size of RAM (if supported by driver).

-[no]confirm_quit

Display confirm quit screen on exit. Default is ON (-confirm_quit).

-[no]ui_mouse

Display UI mouse cursor. Default is OFF (-noui_mouse).

-autoboot_command, -ab command

Command string to execute after machine boot (in quotes ""). To issue a quote to the emulation, use """ in the string. Using \n will issue a create a new line, issuing what was typed prior as a command. Example: -autoboot_command "load """$""",8,1\n".

-autoboot_delay [value]

Timer delay (in seconds) to trigger command execution on autoboot. Default is 2.

-autoboot_script, -script [filename.lua]

File containing scripting to execute after machine boot.

-[no]http

Enable local http server. Default is OFF (-nohttp).

-http_port port

Internal webserver listener port.

-http_path path

Path to web files. Default is /usr/share/games/mess/web.

-[no]console

Enable emulator LUA console. Default is OFF (-noconsole).

-[no]plugins

Enable LUA plugin support. Default is ON (-plugins).

-plugin value

List of plugins to enable.

-noplugin value

List of plugins to disable.

-language, -lang value

Display language. Default is 'English'.

-newui, -nu

Use the new MESS UI.

-watchdog value

Specifies a number of seconds after which MESS should automatically exit if it detects that the emulation has locked up.