Last‐modified:
DGen/SDL is a free, open source emulator for Sega Genesis/Mega Drive systems. DGen was originally written by Dave, then ported to SDL by Joe Groff and Phil K. Hornung in 1998.
Unfortunately, the project was abandoned at least since 2005 and much of its history gone with its original home page.
In 2008, tamentis decided to try to relive DGen/SDL by registering this project on SourceForge and made the source code of the last official release (version 1.23) available through CVS. He also created DGen's logo.
In August 2011, suddenly remembering Streets of Rage, I struggled to find a Mega Drive (Genesis) emulator able to run it on my current setup (Linux/x86_64), as most of them either targeted Windows, were completely written in x86 assembly, or just didn't work for some reason.
Because DGen was my emulator of choice since 2002, I resolved to have a look at the code and make it 64‐bit‐safe myself (only one month later, I found out that some people on some forums already created patches for this purpose). After that and some additional bugfixing, I noticed that tamentis was looking for a new maintainer, so I offered my help along with a bunch of patches and got the position.
DGen isn't the best Mega Drive/Genesis emulator out there, but it works and it's probably the most portable. It's also perfect for command‐line freaks.
— zamaz
You can fetch the last release here:
http://sourceforge.net/projects/dgen/files/dgen/
If you prefer bleeding edge code or want to improve DGen/SDL, use the main git
repository instead:
https://sourceforge.net/p/dgen/dgen/
For bugs and feature requests, please use the SourceForge Tracker. Otherwise by e-mail or on IRC. We can be reached on Freenode, in #DGen.
We also have a Twitter account @dgen_emulator .
Documentation can be found in the source tarballs, it's also provided below for reference but may not be as up‐to‐date.
DGEN(1) BSD General Commands Manual DGEN(1)
NAME
dgen — Sega Genesis/Mega Drive emulator
SYNOPSIS
dgen [-Pfhmv] [-R (J|U|E)] [-H HZ] [-D DEMONAME] [-d DEMONAME] [-n USEC]
[-p CODE,CODE...] [-r RCFILE] [-X XFACT] [-Y YFACT] [-S FACT]
[-g (0|1)] [-G XxY] [-s SLOT] [romname [...]]
DESCRIPTION
The ROM image in the file romname is executed, as emulated on a Sega Gen‐
esis or Mega Drive running in 60Hz NTSC mode (unless the -P option is
specified, in which case 50Hz PAL mode is used). romname should be in
raw binary or SMD format, and may be compressed with gzip(1), zip(1), or
bzip2(1).
When romname isn't specified, DGen starts without a ROM. It can be loaded
later from the prompt. When more than a single romname is specified, they
are executed sequentially.
The options are as follows:
-H HZ Use a custom frame rate, can be used to accelerate or slow
down emulation.
-P Emulate 50Hz PAL mode (as used in European models of the Mega
Drive).
-R (J|U|E) Emulator region. Without this option, DGen uses the first
region mentioned in the ROM header. It should be combined
with -P for PAL mode. See below.
(none) Autodetect (NTSC, 60Hz)
-P Autodetect (PAL, 50Hz)
-R J Japan (NTSC, 60Hz)
-R J -P Japan (PAL, 50Hz)
-R E Europe (NTSC, 60Hz, music will certainly play too
fast)
-R E -P Europe (PAL, 50Hz)
-R U America (NTSC, 60Hz)
-R U -P Same as -R E -P
-f Run fullscreen, if possible.
-h Show a brief synopsis of all options.
-m MinGW only. This option prevents DGen from detaching from its
control console.
-v Show the version number, and exit.
-D DEMONAME
Play back a demo recorded with the -d option.
-d DEMONAME
Record a demo of the program running, which can be later
replayed with the -D switch.
-n USEC Sleep for a number of microseconds after every frame, to give
time to other processes.
-p CODE,CODE...
Modify the ROM image in memory, using Game Genie or Hex style
codes. Game Genie codes are of the form ABCD-EFGH and Hex
codes are in the form 123456:ABCD. To specify more than one
code, separate them with commas (do not use spaces).
-r RCFILE Parse another rc file after $HOME/.dgen/dgenrc. Values in the
specified file override those in the preceding files.
-X XFACT Scale the window XFACT times in the X direction. XFACT must
be a positive integer.
-Y YFACT Scale the window YFACT times in the Y direction. YFACT must
be a positive integer.
-S FACT Scale the window FACT times in both directions. FACT must be
a positive integer.
-g (0|1) Enable/disable OpenGL (if compiled-in).
-G XxY Desired window size (e.g. 640x480, 800x600, etc.)
-s SLOT Load the saved state from the given slot at startup (0-9)
INTERACTIVE PROMPT
A minimalist interactive prompt inspired from vi(1) can be used to per‐
form various operations described below. It is triggered by pressing
colon (:), the default key. Command-line editing, history and completion
are supported.
Commands
{quit, exit, q}
Quit, or load the next romname from command-line, if any.
{load, open, plug, o} filename
Load a given ROM filename.
{unload, close, unplug}
Unload the current ROM.
config_load filename
Load configuration from file filename.
config_save filename
Save current configuration to file filename.
reset
Genesis reset.
{ctv_push, ctv_pop, ctv_none}
Manage the stack of Crap TV filters (if compiled-in).
calibrate number
Interactive calibration of the specified gamepad (1 or 2). If
number isn't specified, default to 1.
unbind binding [...]
Remove specified bindings (variables prefixed with "bind_"). See
dgenrc(5) for more information about them.
vgmdump start filename
vgmdump stop
Manages VGM dumping/logging. If the second argument is start VGM
dumping will be started at the path specified by the third argu‐
ment. If the second argument is stop VGM dumping will be stopped
and the dump finalized.
Variables
All configuration variables from dgenrc(5) can be displayed and modified
interactively, with immediate effect.
{int_name, bool_name, key_name, joy_name, ...} {value}
Affect value to variable name.
{int_name, bool_name, key_name, joy_name, ...}
Display current value for variable name.
FILES
$HOME/.dgen/dgenrc Contains user settings for the emulator.
$HOME/.dgen/dgenrc.auto Generated file containing saved user settings.
$HOME/.dgen/saves/* Save states generated by the emulator.
$HOME/.dgen/ram/* Battery-backup RAM images, generated by the
emulator for ROMs with save RAM.
$HOME/.dgen/screenshots/*
Screenshots are generated there.
$HOME/.dgen/roms/* ROMs default search path.
$HOME/.dgen/demos/* Demos default search path.
SEE ALSO
gzip(1), bzip2(1), zip(1), dgenrc(5)
AUTHORS
This manual page was written by Joe Groff ⟨joe@pknet.com⟩.
Updated by zamaz ⟨zamaz@users.sourceforge.net⟩.
BUGS
There are known emulation bugs, see BUGS in DGen source package.
Report bugs to ⟨http://sourceforge.net/projects/dgen/⟩.
BSD July 26, 2014 BSD
DGENRC(5) BSD File Formats Manual DGENRC(5)
NAME
dgenrc — file containing settings for dgen(1)
SYNOPSIS
$HOME/.dgen/dgenrc
DESCRIPTION
The file $HOME/.dgen/dgenrc is parsed by dgen(1) when the emuator is
started. It is used to set controller keys, as well as other characteris‐
tics of the emulation. The contents of this file may be overriden with
the contents of another similarly-formatted file, via the -r commandline
switch.
FILE FORMAT
Each rc file consists of an unlimited number of lines, which each have
the format 'fieldname = value'. A line may also be a comment, if it
begins with the hash mark (#) character.
Each fieldname is prepended by a name, which identifies the type of this
field:
key_* A key value. May be set to a key identifier listed in the KEY
IDENTIFIERS section below.
joy_* A joystick/joypad value. May be set to a joystick identifier
listed in the JOYSTICK IDENTIFIERS section below.
mou_* A mouse action. May be set to a mouse identifier listed in the
MOUSE IDENTIFIERS section below.
bool_* A boolean value. "false", "no", and "0" values are taken as
false, while "true", "yes", and any number except 0 are taken as
true.
int_* An integer value, greater than or equal to 0.
str_* A string value, can be empty.
Some fields take special value sets, which are addressed in their respec‐
tive sections. None of the field names or values are case-sensitive.
The fields fall under a few basic groups. They are listed below, with
their default values in brackets ([]):
All of them can be modified interactively from the prompt, as described
in dgen(1).
CONTROLLERS
key_pad1_up [up]
key_pad1_down [down]
key_pad1_left [left]
key_pad1_right [right]
key_pad1_a [a]
key_pad1_b [s]
key_pad1_c [d]
key_pad1_x [q]
key_pad1_y [w]
key_pad1_z [e]
key_pad1_mode [backspace]
key_pad1_start [return]
Map keys to the first Genesis controller. Each of these fields has
a corresponding "key_pad2" field, to map to the second controller.
joy_pad1_up [joystick0-axis1-min]
joy_pad1_down [joystick0-axis1-max]
joy_pad1_left [joystick0-axis0-min]
joy_pad1_right [joystick0-axis0-max]
joy_pad1_a [joystick0-button0]
joy_pad1_b [joystick0-button3]
joy_pad1_c [joystick0-button1]
joy_pad1_x [joystick0-button6]
joy_pad1_y [joystick0-button4]
joy_pad1_z [joystick0-button5]
joy_pad1_mode [joystick0-button9]
joy_pad1_start [joystick0-button8]
Map joystick/joypad buttons to the first Genesis controller. Each
of these fields has a corresponding "joy_pad2" field, to map to the
second controller.
bool_joystick [true]
Use joysticks to emulate the controllers. Note that the keyboard
keys will still work if this value is set. This field is only
available if you have joystick support enabled.
int_mouse_delay [50]
Number of milliseconds to wait after the last mouse motion event to
release buttons bound to such events.
USER-DEFINED BINDINGS
bind_{keysym} action
bind_{joypad} action
bind_{mouse} action
Defines a new keyboard, joystick/joypad or mouse binding to an
arbitrary action. These variables use the keysym format as defined
in KEY IDENTIFIERS, the joypad format as defined in JOYSTICK
IDENTIFIERS, or the mouse format as defined in MOUSE IDENTIFIERS.
When action is prefixed with "key_", "joy_" or "mou_", it becomes
an alias to the corresponding variable in CONTROLLERS. Otherwise,
it is interpreted as if entered at the prompt, and can be used to
modify variables or execute commands (see dgenrc(5) for more infor‐
mation). No bindings are defined by default.
bind_"{keysym|joypad|mouse} [{keysym|joypad|mouse} [...]]" action
Alternate syntax that supports combining several identifiers to
perform action. Controller types can be mixed. Identifiers are
separated by spaces. To avoid syntax errors, spaces must be prop‐
erly escaped or quoted.
AUDIO
bool_sound [true]
Enable the sound subsystem.
int_soundrate [44100]
Sound frequency to play at, in hertz (Hz).
int_soundsegs [8]
Number of sound segments to use for sound buffering. Lower values
guarantee low latency. Increment this only if the sound becomes
choppy.
int_soundsamples [0]
Size of the system sound buffer, in samples (samples are the sound
unit, sound rate is how many of them are played every second).
Specifying 0 automatically choses the safest value. If you experi‐
ence sound issues int_soundsegs is unable to solve, try to change
this. Increasing it will cause noticeable audio lag (it is unfortu‐
nately often required on slower machines).
int_volume [100]
Volume level, in percent. Values above 100 cause distorsion.
key_volume_inc [=]
key_volume_dec [-]
joy_volume_inc []
joy_volume_dec []
mou_volume_inc []
mou_volume_dec []
Bindings for volume control.
bool_mjazz [false]
MJazz option - puts 2 more FM chips in the Megadrive for a sort of
22 channel sound boost. Can sound good. Slows things down a lot.
VIDEO
int_depth [0]
Color depth (bits per pixel). Allowed values are 0 (automatic), 8,
15, 16, 24 and 32. Ignored in OpenGL mode.
int_width [-1]
int_height [-1]
Desired window width and height.
bool_opengl [true]
Use the OpenGL renderer, if it is available.
bool_opengl_stretch [true]
Let OpenGL stretch the screen.
bool_opengl_linear [true]
Use GL_LINEAR for textures filtering instead of GL_NEAREST.
bool_opengl_32bit [true]
Use 32 bit textures. They require more memory but are usually
faster than 16 bit textures.
bool_opengl_square [false]
Use square textures. Wastes a lot of memory but may solve OpenGL
initialization failures.
bool_fullscreen [false]
Try to run fullscreen, if possible.
int_scale [-1]
int_scale_x [-1]
int_scale_y [-1]
Amount by which to scale the rendered screen from the default reso‐
lution. See scaling filters.
bool_aspect [true]
Retain original aspect ratio when resizing window.
key_fullscreen_toggle [alt-enter]
joy_fullscreen_toggle []
mou_fullscreen_toggle []
Button to toggle fullscreen mode (this may do nothing if SDL
doesn't support fullscreen toggling on your platform.)
int_info_height [-1]
Height of the text area at the bottom of the screen, in pixels.
This also affects the font size. Values smaller than the minimum
font size make DGen redirect text to stdout instead. The default
value of -1 makes DGen choose the proper height.
bool_fps [false]
Display the current number of frames per second.
bool_buttons [false]
Display pressed buttons. Can be used to help configuring them.
bool_swab [false]
Swap bytes in the video output. Sometimes useful when video output
is located on a different system. This is implemented as a CTV fil‐
ter which must be compiled-in to work.
bool_doublebuffer [true]
Toggle double buffering. Enabling this should prevent screen tear‐
ing from happening. Disabling this may improve the number of dis‐
played frames per second on some systems.
bool_screen_thread [false]
When enabled, a separate thread is created to offload the display‐
ing of frames. This is only useful on slower machines where flip‐
ping video buffers takes time, especially when V-sync is enabled
and doing so blocks until the next frame without consuming CPU time
(sometimes the case when bool_doublebuffer is enabled). This cur‐
rently has no effect when OpenGL is enabled and only works if
multi-threading support is compiled-in.
SAVE STATES
key_slot_X [X]
joy_slot_X []
mou_slot_X []
Sets the current save-state slot to number X.
key_slot_next [f8]
joy_slot_next []
mou_slot_next []
Switch to the next save-slot.
key_slot_prev [f7]
joy_slot_prev []
mou_slot_prev []
Switch to the previous save-slot.
key_save [f2]
joy_save []
mou_save []
Saves state to the current slot.
key_load [f3]
joy_load []
mou_load []
Loads state from the current slot.
MISCELLANEOUS KEYS
key_fix_checksum [f1]
joy_fix_checksum []
mou_fix_checksum []
Fixes the checksum value. Some older games will freeze with a red
screen if the ROM has been hacked or modified with Game Genie
codes. If it does, pressing this, and resetting should fix the
problem.
key_quit [escape]
joy_quit []
mou_quit []
Exit DGen or switch to the next ROM on the command-line.
key_craptv_toggle [f5]
joy_craptv_toggle []
mou_craptv_toggle []
Toggles Crap-TV image filters. These filters aren't available in 8
bpp mode.
key_scaling_toggle [f6]
joy_scaling_toggle []
mou_scaling_toggle []
Toggles scaling algorithms. See scaling_startup below.
key_reset [tab]
joy_reset []
mou_reset []
Restart the Genesis emulation.
key_cpu_toggle [f11]
joy_cpu_toggle []
mou_cpu_toggle []
Switch CPU emulators. The x86 assembly CPU emulator StarScream is
fast, but has glitches which affect a few games. Switching to the
slower Musashi core will fix these problems, at a speed penalty.
key_z80_toggle [f10]
joy_z80_toggle []
mou_z80_toggle []
Switch Z80 emulators. MZ80 is a bit faster than CZ80, particularly
in its assembly version (only available for x86), but CZ80 works
with more games. This key can also disable Z80 emulation.
key_stop [z]
joy_stop []
mou_stop []
Pause emulation, so you can concentrate on real life for a few sec‐
onds. :)
key_game_genie [f9]
joy_game_genie []
mou_game_genie []
Enter a Game Genie or Hex code. This key also works in stopped
mode.
key_screenshot [f12]
joy_screenshot []
mou_screenshot []
Take a screenshot. Not available in 8 bpp mode.
key_prompt [:]
joy_prompt []
mou_prompt []
Pause emulation and display interactive prompt. Also works in
stopped mode.
key_debug_enter [`]
joy_debug_enter []
mou_debug_enter []
Break into the debugger. Only meaningful if debugger support is
compiled-in.
PREFERENCES
int_hz [60]
Video refresh rate. The default is 60 as in NTSC consoles.
bool_pal [false]
When true, a PAL console is emulated. This should be used in combi‐
nation with int_hz above for 50Hz emulation.
region [' ']
U for America (NTSC), E for Europe (PAL), J for Japan (NTSC), X for
Japan (PAL), or empty space for autodetection (the default). Over‐
rides bool_pal and int_hz.
str_region_order [JUEX]
Regions DGen is allowed to emulate when autodetection is enabled,
ordered by preference.
emu_m68k_startup [musa]
Useful when both Musashi and StarScream are compiled-in. This
option selects the default emulator to use ("musa" for Musashi,
"star" for StarScream, "none" for neither). See key_cpu_toggle.
emu_z80_startup [cz80]
Useful when both CZ80 and MZ80 are compiled-in. This option selects
the default emulator to use ("cz80", "mz80" or "none", if you want
to disable it altogether). See key_z80_toggle.
bool_autoload [false]
Automatically load the saved state from slot 0 when DGen starts.
bool_autosave [false]
Automatically save the saved state to slot 0 upon exit. Setting
both of these fields true, you can exit DGen, and automatically
start a game where you left off when you start it again.
bool_autoconf [true]
Automatically dump the current configuration to dgenrc.auto before
exiting. This file is always loaded before dgenrc at startup.
bool_frameskip [true]
Automatically skip frames, when it is necessary to maintain proper
emulation speed. You may want to disable sound or set int_nice to a
nonzero value when setting this to false.
int_nice [0]
If set to a non-zero value, DGen will call usleep(3) with the spec‐
ified parameter after rendering each frame. This will slow the pro‐
gram down (if it is running too fast on your computer), and allow
the operating system to reclaim some CPU time.
ctv_craptv_startup [off]
CTV filter to use by default. Available filters are "blur", "scan‐
line", "interlace" and "swab".
scaling_startup [stretch]
Scaler to use when display resolution is larger than original
screen. Available filters are "stretch", "scale", "hqx", "hqx
stretch", "scale2x", "scale2x stretch" and "none".
bool_show_carthead [false]
Show cartridge header info at startup.
bool_raw_screenshots [false]
Generate unfiltered screenshots.
str_rom_path ["roms"]
Directory where DGen should look for ROMs by default. It's relative
to DGen's home directory, unless an absolute path is provided.
DEBUGGING
bool_vdp_hide_plane_a [false]
bool_vdp_hide_plane_b [false]
bool_vdp_hide_plane_w [false]
bool_vdp_hide_sprites [false]
Hide various planes during frame rendering. Require VDP debugging
to be compiled-in.
bool_vdp_sprites_boxing [false]
int_vdp_sprites_boxing_fg [0xffff00] (yellow)
int_vdp_sprites_boxing_bg [0x00ff00] (green)
Toggle sprites boxing and configure its colors. Require VDP debug‐
ging to be compiled-in. "fg" is for sprites with the high priority
bit set, "bg" is for the others. Color format is 0xRRGGBB.
EXAMPLES
See the file "sample.dgenrc" in the DGen/SDL distribution.
KEY IDENTIFIERS
A key identifier can have the prefixes "shift-", "ctrl-", "alt-" and
"meta-", or any combination thereof, to require that the specified modi‐
fier be pressed in combination with the key. For example, the identifier
"alt-enter" would correspond to holding down the Alt key while pressing
Enter.
The "shift-" modifier only works with keys that don't generate symbols
(such as arrow keys). Otherwise their UTF-8 representation must be used
directly.
The numbers "0" through "9" ("kp_0" through "kp_9" for the numeric key‐
pad), letters "A" through "Z", and function keys "F1" through "F12" map
to their key equivalents. In addition, the following identifiers map to
their similarly-labeled key counterparts. Identifiers on the same line
map to the same key:
escape
backspace
tab
capslock caps_lock
lshift shift_l
rshift shift_r
lctrl ctrl_l
lmeta meta_l
lalt alt_l
ralt alt_r
rmeta meta_r
rctrl ctrl_r
return enter
space
scrollock scroll_lock
numlock num_lock
insert
home
page_up pageup
delete
end
page_down pagedown
left
right
up
down
kp_home
kp_up
kp_pageup kp_page_up
kp_left
kp_right
kp_end
kp_down
kp_pagedown kp_page_down
kp_insert
kp_delete kp_period
kp_enter
kp_divide
kp_minus
kp_multiply
kp_plus
JOYSTICK IDENTIFIERS
Like key identifiers, joystick (or joypad) identifiers describe a joy‐
stick event. Each detected joystick is numbered starting from 0. Three
different event types are supported.
Buttons: joystickX-buttonY
For joystick/joypad number X, button number Y. "button" can be
abbreviated as "b".
Axes: joystickX-axisY-min, joystickX-axisY-max
For joystick/joypad number X, axis number Y, and its position,
which is either "min" (also "n", "negative") or "max" (also "p",
"positive"). "axis" can be abbreviated as "a".
Hats: joystickX-hatY-{direction}
For joystick/joypad number X, hat number Y and direction. "hat" can
be abbreviated as "h". Possible directions are "up", "right",
"down", "left".
MOUSE IDENTIFIERS
These identifiers describe a mouse event. Each detected mouse is numbered
starting from 0. Two different event types are supported.
Buttons: mouseX-buttonY
For mouse number X, button number Y. "button" can be abbreviated as
"b".
Motions: mouseX-{direction}
For mouse number X and direction. Possible directions are "up",
"right", "down", "left".
SEE ALSO
dgen(1)
AUTHORS
This manual page was written by Joe Groff ⟨joe@pknet.com⟩.
Updated by zamaz ⟨zamaz@users.sourceforge.net⟩.
BSD July 26, 2014 BSD