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OK, problems with two ROMs

#1 User is offline Sik 

Posted 01 December 2007 - 03:54 PM

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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 User is offline nineko 

Posted 01 December 2007 - 04:58 PM

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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 User is offline Sik 

Posted 01 December 2007 - 05:48 PM

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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 User is offline Hivebrain 

Posted 01 December 2007 - 07:05 PM

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I thought [c] was a custom checksum routine.

#5 User is offline nineko 

Posted 01 December 2007 - 08:56 PM

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View PostHivebrain, on Dec 2 2007, 01:05 AM, said:

I thought [c] was a custom checksum routine.
Oh, I don't really know how those codes work, I just quoted what I found here: http://info.sonicretro.org/GoodXXXX.

#6 User is offline Skaarg 

Posted 02 December 2007 - 04:11 AM

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I don't know about the Mulan ROM, but I do know the Rockman X3 ROM is a crappy homebrew pirate. Has horid collision and the physics are screwy. The version I do have works so if you want it I can upload it or something.

http://img404.images...8752/x31dr4.png
http://img258.images...9831/x32fk5.png

#7 User is offline Armada 

Posted 02 December 2007 - 06:53 PM

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I love the presence of a giant "XD" in the first screen.

#8 User is offline ICEknight 

Posted 04 December 2007 - 09:09 AM

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Your answer is here.

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

Quote

Mulan (Can't start a game)
006036:E000
Other codes might be needed

RockMan X 3 ("Decode error" message)
0C8B06:6000
0C8B90:6036



Credit goes to TascoDLX.

#9 User is offline Tweaker 

Posted 04 December 2007 - 10:22 AM

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

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

#10 User is offline drx 

Posted 04 December 2007 - 02:00 PM

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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 User is offline Sik 

Posted 08 December 2007 - 02:00 PM

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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...

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