IGS PGM dual frequency oscillator DFO ?

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    • IGS PGM dual frequency oscillator DFO ?

      Hi guys,

      i'm planning to mod my Neogeo MVS with the DFO. nfggames.com/forum2/index.php?topic=5744.0

      Off course, i have no problem running the MVS or PGM on my sony PVM but i'm having issue with my Panasonic HDTV throught my OSSC. My Tv doesnt accept odd video frequency as the Neogeo MVS and IGS PGM.

      The neogeo DFO mod is documented but i found nothing for the PGM.

      Is it doable ? What is the stock oscillator frequency ?

      p.s: i know this mod will change a little the game speed. This mod would be only to play once in a while on my HDTV with pixel perfect RGB signal!

      thx

      Simon
    • I don’t know, but you could use something like an iScan DVDO in your video chain to stabilize any board to 60hz, rather than mod every board with a DFO.

      videogameperfection.com/2016/05/25/iscan-vp50-pro/

      Anyway maybe someone will chime in, but if not that’s an option.
      multis: cps* ttx1/2 gnet f3 mvs sega st-v/16b/24/c2/naomi(netboot) sys2x6 m72
      cabs: sega blast city x2 | taito vewlix c + egret ii
      links: klov/vaps games list | custom fight sticks
      projects: re2 stuff, back to conversions
    • If you can find some info regarding pixel clock on the PGM it would be straight forward to calculate...

      nam9 wrote:

      I don't know what refresh rates the CPS1 boards put out, but you could find crystal timings that would correct to 59.94Hz as well as offer a '10'&'12'Hz switch.

      For the Neo Geo:
      1. 24.000000MHz main clock / 4 = 6.000000MHz pixel clock
      2. 6MHz / 384 pixel clocks per line = 15.625kHz horizontal rate
      3. 15.625kHz / 264 lines = 59.1856 frames/second
      Update.

      For the CPS1/2:
      1. ??? = 8.000000MHz pixel clock
      2. 8MHz / 512 pixel clocks per line = 15.625kHz horizontal rate
      3. 15.625kHz / 262 lines = 59.6374 frames/second
      Anyone know how the pixel clock is derived on the CPS1/2?
    • A modder i know is on the investigation about this. We think the main crystal is the 50MHz one but we are not sure yet.

      After that, this seems like simple math!

      Can someone confirm that the 50MHZ crystal is the one responsible of the video output frequency?

      nam9 wrote:

      If you can find some info regarding pixel clock on the PGM it would be straight forward to calculate...

      nam9 wrote:

      I don't know what refresh rates the CPS1 boards put out, but you could find crystal timings that would correct to 59.94Hz as well as offer a '10'&'12'Hz switch.

      For the Neo Geo:
      1. 24.000000MHz main clock / 4 = 6.000000MHz pixel clock
      2. 6MHz / 384 pixel clocks per line = 15.625kHz horizontal rate
      3. 15.625kHz / 264 lines = 59.1856 frames/second
      Update.

      For the CPS1/2:
      1. ??? = 8.000000MHz pixel clock
      2. 8MHz / 512 pixel clocks per line = 15.625kHz horizontal rate
      3. 15.625kHz / 262 lines = 59.6374 frames/second
      Anyone know how the pixel clock is derived on the CPS1/2?


      Thx, already thought about the DVDO or Extron DSC 301HD.

      i found the DFO to be a good option because of how simple it is to install.

      Myabe i'll end up buying one of these !


      ekorz wrote:

      I don’t know, but you could use something like an iScan DVDO in your video chain to stabilize any board to 60hz, rather than mod every board with a DFO.

      videogameperfection.com/2016/05/25/iscan-vp50-pro/

      Anyway maybe someone will chime in, but if not that’s an option.
    • From the above link:

      IGS PolyGame Master (PGM) (pgm.cpp): Some games for the standard cartridge system check for 60.0 +/- 0.1 Hz refresh in POST; best guesses for these are:
      MCFG_SCREEN_RAW_PARAMS(33868800/4, 560, 0/*+x*/, 448/*+x*/, 252, 0/*+y*/, 224/*+y*/) ()
      MCFG_SCREEN_RAW_PARAMS(XTAL_50MHz/6, 591, 0/*+x*/, 448/*+x*/, 235, 0/*+y*/, 224/*+y*/) ()
      MCFG_SCREEN_RAW_PARAMS(10000000, 615, 0/*+x*/, 448/*+x*/, 271, 0/*+y*/, 224/*+y*/) (from either 50MHz/5 or 20MHz/2)
      MCFG_SCREEN_RAW_PARAMS(10000000, 646, 0/*+x*/, 448/*+x*/, 258, 0/*+y*/, 224/*+y*/) ()
      MCFG_SCREEN_RAW_PARAMS(10000000, 641, 0/*+x*/, 448/*+x*/, 260, 0/*+y*/, 224/*+y*/) ()
      MCFG_SCREEN_RAW_PARAMS(10000000, 624, 0/*+x*/, 448/*+x*/, 267, 0/*+y*/, 224/*+y*/) ()
      The dedicated-PCB games developed by CAVE were measured at 59.17 Hz, or more precisely 59.168391?. Best guesses for these are:
      MCFG_SCREEN_RAW_PARAMS(33868800/4, 540, 0/*+x*/, 448/*+x*/, 265, 0/*+y*/, 224/*+y*/) ()
      MCFG_SCREEN_RAW_PARAMS(XTAL_50MHz/6, 548, 0/*+x*/, 448/*+x*/, 257, 0/*+y*/, 224/*+y*/) (not sure whether the 50MHz crystal from the standard PGM motherboard exists here)
      MCFG_SCREEN_RAW_PARAMS(10000000, 593, 0/*+x*/, 448/*+x*/, 285, 0/*+y*/, 224/*+y*/) ()
      MCFG_SCREEN_RAW_PARAMS(10000000, 655, 0/*+x*/, 448/*+x*/, 258, 0/*+y*/, 224/*+y*/) (assuming CAVE PCBs differ from the generic motherboard only in horizontal dot count)
      MCFG_SCREEN_RAW_PARAMS(10000000, 650, 0/*+x*/, 448/*+x*/, 260, 0/*+y*/, 224/*+y*/) (ditto)
      MCFG_SCREEN_RAW_PARAMS(10000000, 633, 0/*+x*/, 448/*+x*/, 267, 0/*+y*/, 224/*+y*/) (ditto)

      Does... that mean different games derive different pixel clocks?