bitbytebit: It looks standard. 15.1 - 16.8 kHz horizontal, 47 - 63 Hz vertical. Resolution 560x240 lines.
Here is the output from "groovymame -verbose -md 4 dkong"
Parsing mame.ini
Parsing mame.ini
Monitor: generic Orientation: horizontal
MonitorLimits 15725.00-15750.00,50.00-60.00,2.000,4.700,8.000,0.064,0.192,1.024,0,0,288.0,448
# dkong [11] 400x256@57.07 15.7500Khz
ModeLine "400x256x57.07" 8.190000 400 416 456 520 256 257 260 276 -HSync -VSync
SwitchRes [dkong] (1) vertical (256x224@60.61)->(400x256@60.61)->(400x256@57.07)
# dkong 400x256@57.07 15.7500Khz
ModeLine "400x256x57.07" 8.190000 400 416 456 520 256 257 260 276 -HSync -VSync
ADD VGA-0: ModeLine "400x256x57.07" 8.190000 400 416 456 520 256 257 260 276 -HSync -VSync
SwitchRes Running 'xrandr --newmode "400x256x57.07" 8.190000 400 416 456 520 256 257 260 276 -HSync -VSync'
SwitchRes Running 'xrandr --addmode VGA-0 "400x256x57.07"'
Setting SDL audiodriver 'dsp' ...
Build version: 0.141u3 (Mar 5 2011)
Build architecure: SDLMAME_ARCH=
Build defines 1: SDLMAME_UNIX=1 SDLMAME_LINUX=1
Build defines 1: LSB_FIRST=1 DISTRO=generic SYNC_IMPLEMENTATION=tc
SDL/OpenGL defines: SDL_COMPILEDVERSION=1214 USE_OPENGL=1 USE_DISPATCH_GL=1
Compiler defines A: __GNUC__=4 __GNUC_MINOR__=4 __GNUC_PATCHLEVEL__=4 __VERSION__="4.4.4"
Compiler defines B: __unix__=1 __i386__=1
Compiler defines C: __USE_FORTIFY_LEVEL=0
SDL Device Driver : x11
SDL Monitor Dimensions: 648 x 480
Enter sdlwindow_init
Using SDL single-window OpenGL driver (SDL 1.2)
Leave sdlwindow_init
648x 480 -> 0.001541
400x 256 -> 2.000000
Loaded opengl shared library: <default>
OpenGL: Tungsten Graphics, Inc.
OpenGL: Mesa DRI R100 (RV200 5157) 20090101 x86/MMX/SSE2 TCL DRI2
OpenGL: 1.3 Mesa 7.9.1
OpenGL: texture rectangle supported
OpenGL: non-power-of-2 textures supported (old method)
OpenGL: vertex buffer supported
OpenGL: pixel buffers not supported
OpenGL: framebuffer object supported
OpenGL: GLSL not supported
OpenGL: max texture size 2048 x 2048
Keyboard: Start initialization
Input: Adding Kbd #1: System keyboard
Keyboard: Registered System keyboard
Keyboard: End initialization
Mouse: Start initialization
Input: Adding Mouse #1: System mouse
Mouse: Registered System mouse
Mouse: End initialization
Joystick: Start initialization
Joystick: End initialization
Audio: Start initialization
Audio: Driver is dsp
Audio: frequency: 48000, channels: 2, samples: 512
sdl_create_buffers: creating stream buffer of 57344 bytes
Audio: End initialization
ouput: unable to open output notifier file /tmp/sdlmame_out
Input: Changing default joystick map = s8.4s8.44s8.4445
s8888888s
4s88888s6
44s888s66
444555666
444555666
444555666
44s222s66
4s22222s6
s2222222s
Input: Changing default joystick map = s8.4s8.44s8.4445
s8888888s
4s88888s6
44s888s66
444555666
444555666
444555666
44s222s66
4s22222s6
s2222222s
Starting Driver Device 'root'
(missing dependencies; rescheduling)
Starting Z80 'maincpu'
Starting DMA8257 'dma8257'
Starting Video Screen 'screen'
Starting 8 bit latch 'ls175.3d'
Starting 8 bit latch 'ls259.6h'
Starting 8 bit latch 'virtual_p2'
Starting MB8884 'soundcpu'
Starting Speaker 'mono'
(missing dependencies; rescheduling)
Starting DISCRETE 'discrete'
Starting Driver Device 'root'
(missing dependencies; rescheduling)
Starting Speaker 'mono'
Starting Driver Device 'root'
648x 480 -> 0.001541
400x 256 -> 2.000000
OpenGL: VBO supported
OpenGL: FBO supported
OpenGL: using vid filter: 0
GL texture: copy 1, shader 0, dynamic 0, 256x224 256x224 [PALETTE16, Equal: 0, Palette: 1,
scale 1x1, border 0, pitch 384,256/2048], colors: 521, bytes/pix 4
GL texture: copy 1, shader 0, dynamic 0, 256x224 256x224 [PALETTE16, Equal: 0, Palette: 1,
scale 1x1, border 0, pitch 384,256/2048], colors: 521, bytes/pix 4
sdl_kill: closing audio
Joystick: Start deinitialization
Joystick: End deinitialization
Enter sdlwindow_exit
Leave sdlwindow_exit
REMOVE VGA-0: ModeLine "400x256x57.07" 8.190000 400 416 456 520 256 257 260 276 -HSync -VSync
SwitchRes Running 'xrandr --delmode VGA-0 "400x256x57.07"'
SwitchRes Running 'xrandr --rmmode "400x256x57.07"'
Here is my xorg.conf
# Config for generic Monitor and ati Video Card
Section "Monitor"
Identifier "VGA-0"
VendorName "Unknown"
ModelName "Unknown"
HorizSync 15-50
VertRefresh 40-80
Option "DPMS" "False"
Option "DefaultModes" "False"
UseModes "ArcadeModes"
EndSection
Section "Device"
Identifier "Card0"
VendorName "Unknown"
BoardName "Unknown"
Driver "ati"
BusID "PCI:01:00:0"
Option "ModeDebug" "true"
Option "monitor-VGA-0" "VGA-0"
EndSection
Section "Screen"
Identifier "Screen0"
Device "Card0"
Monitor "VGA-0"
DefaultDepth 24
SubSection "Display"
Viewport 0 0
Depth 8
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 16
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 24
EndSubSection
EndSection
Section "Modes"
Identifier "ArcadeModes"
# 648x480@60.00 15.7500Khz
ModeLine "648x480x60.00" 13.230000 648 672 736 840 480 484 490 525 -HSync -VSync interlace
EndSection