Quantcast

Page 1 of 2 12 LastLast
Results 1 to 15 of 25

Thread: Super Skidmarks NTSC patch

  1. #1
    Comrade as in friend. Master of Shinobi ComradeOj's Avatar
    Join Date
    Dec 2012
    Location
    New Mexico, USA
    Age
    26
    Posts
    1,438
    Rep Power
    62

    Default Super Skidmarks NTSC patch

    I decided to take a shot at making the game run on NTSC systems. I think I got it working.

    What I did:

    In various parts of the game, the program sets the VDP to use V30 mode. This makes the screen roll on NTSC, so I patched it to use V28 mode. This may cause some screen cropping though.

    That was only half of the trouble. There was also a DMA transfer routine that caused the screen to fill with garbage on NTSC. I'm not sure why. I just cut the entire routine out, and surprisingly the game still played. The offending routine can be found at $1F910C in the ROM. It only seems to be called from the HBLANK routine.

    This is the offending instruction: MOVE.L #$7C000083, $4(A0)

    At the time of execution, A0 will have the VDP data port ($C00000), which means that the instruction is writing to ($C00004) which is the VDP control port. I'm fairly certain that 7C000083 is telling the VDP to start a DMA transfer. I'm not sure of the source/destination though. All I know is that the game went to hell when it happened.

    Another issue is slowdown. There was some pretty nasty slowdown going on. I'm guessing it's because the game has to draw 60 frames per second instead of 50. I flipped my overclock switch to 10MHZ, and it ran fine though. I'm also assuming that there is some NTSC speed-up going on, since the game and music was made for 50. I don't know for sure since I'm not too familiar with the game.

    I also didn't patch out any artificial region locking. I'm not sure if the game even has a region lock. Please let me know if you run into any issues, so that I can fix them.

    I might make a V2 patch some time in the future that addresses the DMA problem instead of just cutting the routine out, and also fix the slowdown issues.

    Here is the download link to the IPS patch: https://drive.google.com/open?id=0B-...GUyNHhERUg0VEE
    I used LunarIPS to make the patch, if it matters.

    Video:
    Modded consoles:
    Master System (v7040) with s-video & direct AV out
    Model 1 with 10mhz overclock & halt switches
    Model 1 with 10mhz 68010
    Model 2 VA2.3 with unfiltered Mega Amp, & s-video
    Model 3 VA1 with compatibility fixes & s-video
    32X with s-video
    Visit my web site at www.mode5.net
    Or my collection of homebrew Genesis games, programs, and music on SEGA-16!

  2. #2
    Road Rasher
    Join Date
    Jun 2011
    Posts
    484
    Rep Power
    16

    Default

    Finally had some free time to try the patch, but i must be doing something wrong, since the patched file gives me the exact same result as the unpatched rom on my mega everdrive . I will try again tomorrow.

    But jugding from the video, you already did a great job. Thanks!

  3. #3
    Road Rasher
    Join Date
    Jun 2011
    Posts
    484
    Rep Power
    16

    Default

    Tried to get the rom to work one last time before going to sleep, and it did!. Its nice to finally be able to play the game in color, instead of black and white, although other problems arise, as ComradeOj mentions. Anyways i am off to bed with a big smile on my face having played Super Skidmarks in color for a good 15 minutes.

    Thanks ComradeOj!

  4. #4
    Benjamin's Avatar
    Join Date
    Jun 2006
    Location
    New Orleans, LA
    Age
    44
    Posts
    1,594
    Rep Power
    34

    Default

    Quote Originally Posted by ComradeOj View Post
    I also didn't patch out any artificial region locking. I'm not sure if the game even has a region lock. Please let me know if you run into any issues, so that I can fix them.
    The game isn't region locked. When I got mine in, I tried using a converter cartridge hoping that maybe it still needed to be in a PAL mode to play despite booting just fine.

    Is there any possibility of a Game Genie code incorporating your fix?

  5. #5
    Comrade as in friend. Master of Shinobi ComradeOj's Avatar
    Join Date
    Dec 2012
    Location
    New Mexico, USA
    Age
    26
    Posts
    1,438
    Rep Power
    62

    Default

    Quote Originally Posted by saturndual32 View Post
    Tried to get the rom to work one last time before going to sleep, and it did!. Its nice to finally be able to play the game in color, instead of black and white, although other problems arise, as ComradeOj mentions. Anyways i am off to bed with a big smile on my face having played Super Skidmarks in color for a good 15 minutes.

    Thanks ComradeOj!
    Glad you got it working! I'll play around with it a bit more and see if I can get some of the issues smoothed out. I might be able to help the slowdown issue by having it not render the now off-screen portion of the game. Right now, you pretty much have to have an overclocked system to get smooth performance.

    Quote Originally Posted by Benjamin View Post
    The game isn't region locked. When I got mine in, I tried using a converter cartridge hoping that maybe it still needed to be in a PAL mode to play despite booting just fine.

    Is there any possibility of a Game Genie code incorporating your fix?
    If I remember right, I had to make 7 words (14 bytes) worth of changes to the ROM. The Game Genie allows up to 5 words. I might be able to cut out two of the V30/V28 mode changes to hit that 5 code limit. That could cause issues in certain parts of the game. It's worth a shot though. Maybe screen rolling could be tolerated in the menus if the rest of the game was patchable to play correctly with only a game genie.
    Modded consoles:
    Master System (v7040) with s-video & direct AV out
    Model 1 with 10mhz overclock & halt switches
    Model 1 with 10mhz 68010
    Model 2 VA2.3 with unfiltered Mega Amp, & s-video
    Model 3 VA1 with compatibility fixes & s-video
    32X with s-video
    Visit my web site at www.mode5.net
    Or my collection of homebrew Genesis games, programs, and music on SEGA-16!

  6. #6
    Hero of Algol
    Join Date
    Aug 2010
    Posts
    8,090
    Rep Power
    188

    Default

    Sensational work, ComradeOj! Rep given.

    The slowdown is "normal" since Codemasters usually pushed things quite a bit and this game was design around the 50 Hz mode and its longer VBlank time.

  7. #7
    Outrunner Stef's Avatar
    Join Date
    Aug 2011
    Location
    France
    Posts
    622
    Rep Power
    30

    Default

    Super Skidmark is definitely a game using the advantages of the PAL system so i am surprised you were able to patch it for NTSC !
    The DMA command you removed is probably the one used for splitted screen when you play in versus mode, i guess you broken it by removing the DMA command. You can just let the demo play to see the splitted screen versus mode...

  8. #8
    Comrade as in friend. Master of Shinobi ComradeOj's Avatar
    Join Date
    Dec 2012
    Location
    New Mexico, USA
    Age
    26
    Posts
    1,438
    Rep Power
    62

    Default

    Quote Originally Posted by Stef View Post
    Super Skidmark is definitely a game using the advantages of the PAL system so i am surprised you were able to patch it for NTSC !
    The DMA command you removed is probably the one used for splitted screen when you play in versus mode, i guess you broken it by removing the DMA command. You can just let the demo play to see the splitted screen versus mode...
    You're right about the DMA being for split-screen. If you let the demo run, the splitscreen looks really glitched and freezes after a while. I guess I didn't notice because I was impatiently mashing buttons to skip to the game during testing.
    I still want to try to fix the DMA issue, instead of just disabling it. I'm not sure why it glitches so badly when it runs. Maybe it's because PAL has a higher DMA transfer capacity than NTSC?
    Modded consoles:
    Master System (v7040) with s-video & direct AV out
    Model 1 with 10mhz overclock & halt switches
    Model 1 with 10mhz 68010
    Model 2 VA2.3 with unfiltered Mega Amp, & s-video
    Model 3 VA1 with compatibility fixes & s-video
    32X with s-video
    Visit my web site at www.mode5.net
    Or my collection of homebrew Genesis games, programs, and music on SEGA-16!

  9. #9
    Hero of Algol
    Join Date
    Aug 2010
    Posts
    8,090
    Rep Power
    188

    Default

    Quote Originally Posted by ComradeOj View Post
    I'm not sure why it glitches so badly when it runs.
    We're probably talking about tightly timed DMA transfers and VDP writes.
    My blind shot is:
    - In PAL mode it was writing stuff with display off.
    - In NTSC mode VBlank time is shorter, so it's now writing stuff with display on which should be written only with display off, thus causing bad graphical glitches.
    Last edited by Barone; 08-20-2015 at 01:34 PM.

  10. #10
    Outrunner Stef's Avatar
    Join Date
    Aug 2011
    Location
    France
    Posts
    622
    Rep Power
    30

    Default

    ^^
    This

    It's why i said this game is specifically wrote for PAL system. I guess it relies on the extra VRAM bandwidth for the split screen mode.

  11. #11
    Raging in the Streets SEGA.GENESIS1989's Avatar
    Join Date
    Aug 2009
    Location
    Toronto, Ontario, Canada
    Posts
    3,456
    Rep Power
    74

    Default

    Quote Originally Posted by ComradeOj View Post
    Glad you got it working! I'll play around with it a bit more and see if I can get some of the issues smoothed out. I might be able to help the slowdown issue by having it not render the now off-screen portion of the game. Right now, you pretty much have to have an overclocked system to get smooth performance.



    If I remember right, I had to make 7 words (14 bytes) worth of changes to the ROM. The Game Genie allows up to 5 words. I might be able to cut out two of the V30/V28 mode changes to hit that 5 code limit. That could cause issues in certain parts of the game. It's worth a shot though. Maybe screen rolling could be tolerated in the menus if the rest of the game was patchable to play correctly with only a game genie.
    ComradeOj, I was just wondering if you had any success developing an appropriate Game Genie code? Fingers crossed!
    "There's nothing to fear, except fear itself"
    http://i1054.photobucket.com/albums/s486/link2link2link/YUZOKOSHIROISAGODNEOSEEDEDITION.gif

  12. #12
    Comrade as in friend. Master of Shinobi ComradeOj's Avatar
    Join Date
    Dec 2012
    Location
    New Mexico, USA
    Age
    26
    Posts
    1,438
    Rep Power
    62

    Default

    Quote Originally Posted by SEGA.GENESIS1989 View Post
    ComradeOj, I was just wondering if you had any success developing an appropriate Game Genie code? Fingers crossed!
    Yep! I don't call my youtube channel "Genesis Game Genie" for nothing.

    I was able to omit two codes without issues that I could see. It still might screw the game up somewhere else.
    These 5 codes should make the game playable. I don't have the physical game to try, but they worked on my everdrive using the game genie feature.

    RVEA-JDE0
    NVEA-JDHG
    RWGT-JDAR
    NWGT-JDDR
    RRJV-86TN

    These are the codes that were eliminated, in case anyone wants to experiment with which codes can be safely omitted.
    RWJV-8DAA
    RRJV-86TN
    Modded consoles:
    Master System (v7040) with s-video & direct AV out
    Model 1 with 10mhz overclock & halt switches
    Model 1 with 10mhz 68010
    Model 2 VA2.3 with unfiltered Mega Amp, & s-video
    Model 3 VA1 with compatibility fixes & s-video
    32X with s-video
    Visit my web site at www.mode5.net
    Or my collection of homebrew Genesis games, programs, and music on SEGA-16!

  13. #13
    Raging in the Streets SEGA.GENESIS1989's Avatar
    Join Date
    Aug 2009
    Location
    Toronto, Ontario, Canada
    Posts
    3,456
    Rep Power
    74

    Default

    Quote Originally Posted by ComradeOj View Post
    Yep! I don't call my youtube channel "Genesis Game Genie" for nothing.

    I was able to omit two codes without issues that I could see. It still might screw the game up somewhere else.
    These 5 codes should make the game playable. I don't have the physical game to try, but they worked on my everdrive using the game genie feature.

    RVEA-JDE0
    NVEA-JDHG
    RWGT-JDAR
    NWGT-JDDR
    RRJV-86TN

    These are the codes that were eliminated, in case anyone wants to experiment with which codes can be safely omitted.
    RWJV-8DAA
    RRJV-86TN

    Yee haaaaa! And here I thought that this PAL exclusive was unplayable! Thanks ComradeOj! I'll post my feedback in this thread when I get a chance!

    You must spread some Reputation around before giving it to ComradeOj again.

    Someone give this rep for me! He deserves it!
    "There's nothing to fear, except fear itself"
    http://i1054.photobucket.com/albums/s486/link2link2link/YUZOKOSHIROISAGODNEOSEEDEDITION.gif

  14. #14
    Comrade as in friend. Master of Shinobi ComradeOj's Avatar
    Join Date
    Dec 2012
    Location
    New Mexico, USA
    Age
    26
    Posts
    1,438
    Rep Power
    62

    Default

    Quote Originally Posted by SEGA.GENESIS1989 View Post
    Yee haaaaa! And here I thought that this PAL exclusive was unplayable! Thanks ComradeOj! I'll post my feedback in this thread when I get a chance!

    You must spread some Reputation around before giving it to ComradeOj again.

    Someone give this rep for me! He deserves it!
    Thanks! I don't own the actual cartridge, I just test the game genie codes with my everdrive. I hope it works fine on the real deal.

    A game not playable on my NTSC Genesis?


    Some time I'll take a shot at some of the other PAL games with serious issues. I still want to play with skidmarks, trying to smooth out the issues it still has.
    Modded consoles:
    Master System (v7040) with s-video & direct AV out
    Model 1 with 10mhz overclock & halt switches
    Model 1 with 10mhz 68010
    Model 2 VA2.3 with unfiltered Mega Amp, & s-video
    Model 3 VA1 with compatibility fixes & s-video
    32X with s-video
    Visit my web site at www.mode5.net
    Or my collection of homebrew Genesis games, programs, and music on SEGA-16!

  15. #15
    Raging in the Streets SEGA.GENESIS1989's Avatar
    Join Date
    Aug 2009
    Location
    Toronto, Ontario, Canada
    Posts
    3,456
    Rep Power
    74

    Default

    Hey ComradOJ, I have some bad news: I just tried the GG code and the screen rolls right from the onset.
    "There's nothing to fear, except fear itself"
    http://i1054.photobucket.com/albums/s486/link2link2link/YUZOKOSHIROISAGODNEOSEEDEDITION.gif

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •