Gracias, Recap y Calamity, por las respuestas, hace años leí algo sobre un driver para monitor de 15khz, era creo en el foro Marcianitos, a lo mejor os suena un tal Ferix, había modificado un driver de monitor. Nunca pude bajar el archivo para probarlo.
Pego aquí el texto de archivo vmmaker.ini, que comentaba Recap, por si sirve de algo. Utilizo mame32 v0.87. El PC lo tengo dedicado a emuladores y juegos antiguos, cuando uso dosbox y configuración de vídeo a pantalla completa con resolución original es cuando se pone a 31kHz.
; VideoModeMaker - Options
; 1. MAME
; Path for Mame executable, in case we want to extract xml information from it.
MameExe = "D:\Juegos\MAMEplus_087\mame32p.exe"
; Path for Mame ini folder, in case we want to create an ini file for each game.
; Important: existing ini files will be overwritten.
IniPath = "D:\Juegos\MAMEplus_087\ini\"
; Mame options.
ListFromXML = 1 ; Processes Mame XML and get video mode list from it
GenerateXML = 0 ; Extracts XML from Mame (only needed once)
OnlyListMain = 0 ; Only list resolutions for games contained in MameMain.txt
GenerateInis = 1 ; Creates an ini file for each Mame game, in the IniPath folder
SDLMame = 0 ; Use SDLMame specific options
; Monitor orientation
MonitorHorizontal = 1 ; 0 = Rotating monitor: horizontal and vertical games at their native resolution
; Suitable for users that physically rotate their CRTs
; 1 = Horizontal monitor: horizontal games run at their native resolution and
; vertical games are rotated to fit in horizontal monitor
RotatingDesktop = 0 ; Specifies if both desktop and monitor are rotated
; Aspect ratio for vertical games on horizontal monitor
; 4:3 (keeps original aspect ratio)
; 3:3 (stretches to square format)
; 3:4 (stretches to full screen)
; h:v (custom aspect ratio)
VerticalAspect = "3:3"
; 2. MONITOR
; Monitor Type. Valid types: D9800, D9400, D9200, EGA, VGA, MULTI, H9110, PAL, NTSC, GENERIC, CUSTOM
MonitorType = "CUSTOM"
; Monitor CUSTOM. These values will be used if MonitorType = "CUSTOM"
; monitor_specs0-6 HfreqMin-HfreqMax, VfreqMin,VfreqMax, HFrontPorch, HSyncPulse, HBackPorch, VfrontPorch, VSyncPulse, VBackPorch, HSyncPol, VSyncPol, ActiveLinesLimit, VirtualLinesLimit
; * HfreqMin-HfreqMax: Minimum and maximum horizontal frequency, in Hz. Defines the range of horizontal frequencies the monitor is capable to sync.
; The higher the horizontal frequency, the higher the vertical resolution available for the same vertical refresh.
; The higher the horizontal frequency, the higher the vertical refresh available for the same vertical resolution.
; The higher the horizontal frequency, the lower the horizontal amplitude of active video (narrower picture).
; * VFreqMin-VfreqMax: Minimum and maximum vertical frequency, in Hz, Defines the range of vertical frequencies the monitor is capable to sync.
; * HFrontPorch, HSyncPulse, HBackPorch: Horizontal timing and geometry, values in µs
; * VfrontPorch, VSyncPulse, VBackPorch: Vertical timing and geometry, values in ms
; * HSyncPol,VSyncPol: sync polarities, 0 = negative, 1 = positive.
; * ActiveLinesLimit: Vertical resolutions until ActiveLinesLimit value included, are generated as progressive, regardless the possibility
; of obtaining the required vertical refresh value.
; * VirtualLinesLimit: Vertical resolutions above ActiveLinesLimit and below VirtualLinesLimit are virtualized, that is, an interlaced resolution
; bigger that the native one is generated, with the right refresh, and "hardware stretch" is applied.
; Vertical resolutions above VirtulaLinesLimit are generated as interlaced, without any stretching.
monitor_specs0 15200-16300, 49.00-61.00, 2.000, 4.700, 8.000, 0.064, 0.160, 1.056, 0, 0, 288, 448
; Tolerance for horizontal frequency, in kHz, enables extending the range defined by [ HfreqMin, HfreqMax ]
; The resulting allowed frequency range will be [ HfreqMin - HfreqTolerance, HfreqMax + HfreqTolerance ]
HfreqTolerance = 0.010
; 3. MODELINE GENERATOR
; Total number of modelines to generate. Here are the recommended values for each driver version:
; CRT_Emudriver, based on Catalyst 6.5: 160 modes (accepts up to 200, but above 160 HyperSpin will refuse to load)
; CRT_Emudriver, based on Catalyst 9.3: 120 modes (accepts some more but above 120 you can get some blue screens)
; Regular Catalyst : 60 modes (won't accept any more)
TotalModes = 160
; If enabled, only creates modes with 32 bits per pixel color depth
Only32BPPModes = 0
; Method for mode table generation. If Mame xml is processed, that will create a lot of different video modes, so the mode table
; will be optimized keeping the most relevant ones, and dropping the rest, to keep below the TotalModes value.
; 0 = Static table: modelines are generated keeping their original vertical refresh. This method is intended to be used in
; combination with ini files for each game.
; 1 = Dynamic table: a table of dummy modes is created using xres and yres values while ignoring vfreq. This method is intended
; to be used in combination with Switchres or Groovymame. No ini files are required using this method (you should disable the
; GenerateInis option).
; 2 = Magic table: a table of 'magic resolutions' is created, by ignoring xres and vfreq and just keeping yres. This method greatly reduces
; the total number of modes in the list. It's only supported by GroovyMAME, and is intended as a workaround for the Hyperspin issue.
ModeTableMethod_Custom = 0
ModeTableMethod_XML = 0
; Minimum resolution values (these will be used instead of lower values)
XresMin_XML = 224
YresMin_XML = 224
YresRound_XML = 0
XresMin_Custom = 224
YresMin_Custom = 224
YresRound_Custom = 0
; Minimum dotclock value allowed by the video card, in MHz (i.e. DotClockMin = 7.010)
DotClockMin = 0
; Number of iterations used by the mode generator [0,5]. The higher the number of iterations, the bigger the accuracy of the vertical
; refreshed obtained, normally at the cost of increasing the horizontal frequency strictly required.
Iterations = 5
; Specifies if the refresh label is multiplied by 10 before rounding (experimental).
VFreqLabelx10 = 0
; 4. DRIVER
; Path for the driver folder
DriverPath = ".\Driver\"
; If UpdateRegistry is enabled, UpdateDriver will only work if the driver version found in DriverPath matches the one installed
; in the system.
UpdateRegistry = 1 ; Specifies if the video card registry section will be updated with the new video modes
; (will only work in combination with CRT_EMUDriver).
UpdateDriver = 0 ; Specifies if the driver files in DriverPath will be updated with the new video modes, for
; future installations.
AnyCatalyst = 0 ; Allows modelines to be installed for any Catalyst version. This option is experimental and
; known to produce some problems.
Gracias y saludos