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OK, problems with two ROMs

Discussion in 'Technical Discussion' started by Sik, Dec 1, 2007.

  1. Sik

    Sik

    Sik is pronounced as "seek", not as "sick". Tech Member
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    http://www.fileden.com/files/2006/12/22/54...20%5B%21%5D.bin
    http://www.fileden.com/files/2006/12/22/54...20%5B%21%5D.bin

    Those are giving serious trouble to me. I can't get them running in emulators, and I wanna see if anybody out there can try out. Yes, I tried everything, enabling and disabling 32X, the BIOS, the SRAM, fixing the checksum, changing country code, and nothing worked. And I tried both Fusion and Gens.

    The first one is Mulan. I know this one runs in the real hardware because once I had the cart, and it worked more than OK. But in emulators it doesn't get past the title card. I was debugging the game and it seems like it gets stuck in an infinite loop (so it doesn't crash). And this game doesn't do exactly weird things... I think. Does anybody know what may be wrong with it? Maybe it uses some feature that isn't emulated?

    Worse is the case of Rockman X3. It simply gives a "DECODE ERROR" message. For the record, isn't it? Yes, I checked and it seems to be a valid MegaDrive game... The header is incomplete, through. Enough to be able to run with a BIOS, but nothing more. Even more, there's code where the country field goes! Does anybody know how to get it working?

    Thanks in advance and tell me what was the stupidity I was doing :P
     
  2. nineko

    nineko

    I am the Holy Cat Tech Member
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    They won't run. Their classification is [c], and according to the Wiki, [c] means that there is a faulty checksum routine.
     
  3. Sik

    Sik

    Sik is pronounced as "seek", not as "sick". Tech Member
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    Faulty checksum routine? Shouldn't I be able to track that subroutine in the disassembler and then patch the ROM to get it working?

    And by the way, Mulan DOES run. It just crashes after the title screen, and the game DOES work in the real hardware, so unless it's a bad dump there's no reason for it to crash.
     
  4. Hivebrain

    Hivebrain

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    I thought [c] was a custom checksum routine.
     
  5. nineko

    nineko

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    Oh, I don't really know how those codes work, I just quoted what I found here: http://info.sonicretro.org/GoodXXXX.
     
  6. Skaarg

    Skaarg

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  7. Armada

    Armada

    Sometimes I do things Member
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    I love the presence of a giant "XD" in the first screen.
     
  8. ICEknight

    ICEknight

    Researcher Researcher
    Your answer is here.

    You must enter the following PAR codes in order to circunvent the errors:

    Credit goes to TascoDLX.
     
  9. Tweaker

    Tweaker

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    You could probably patch the ROM manually with those...

    Are these problems a result of bad dumps, or what?
     
  10. drx

    drx

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    :rolleyes:
    I have decrypted and/or fixed some games like that before. Most of the time it's either shitty pirates with feeble coding, using some custom mapper / bank switcher which ruins the game. Some of the time the dumps are actually games that use some extra hardware like a decrypter (think arcade), or some kind of funky joypads. Sometimes the hardware is mapped to weird addresses like 0x400000 and either because of an out of bounds error or just simply because the game is waiting for a responce from the additional hardware, it won't get past a certain point.

    Some of these games, especially the unlicensed homebrew games created by pirates (like the Lion King clones) are really interesting.
     
  11. Sik

    Sik

    Sik is pronounced as "seek", not as "sick". Tech Member
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    Apparently somebody already took care of patching the ROMs, so I guess you can lock this topic. However, it's interesting the fact that those pirate games (I know them all are pirate games) look simple and work in the real hardware but they DON'T in emulators. Needs researching. Meanwhile, I'll go with the patched versions...

    Does anybody want to take care of them? I'm really lazy, and I yet have to remake my Sonic 3D disassembly and recover all the lost functionality in VideoLib (I just could recover VideoLib 2) from the last hard disk crash... Ugh...