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View topic - Sega 3D Classics Collection for 3DS ROM inspection
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 Sega 3D Classics Collection for 3DS ROM inspection
 Posted: Sat Dec 02, 2017 11:02 pm
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[Admin: split from http://www.smspower.org/forums/16881-FantasyZoneWithFMMusic ]
Amazing! Ummmmm, would be possible to download Sega 3D Classics Collection for 3DS and extract Fantasy Zone Master System Rom ??? This is bad video but I think it sounds fantastic in FM, ( minute 1'30 ) https://www.youtube.com/watch?v=f3WACkfXTUc |
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Posted: Sun Dec 03, 2017 7:23 am
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| There are people who can decrypt this stuff, the virtual console games are around... | |
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Posted: Sat Dec 09, 2017 11:06 am
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Hi,
i've found & extracted datas from the Sega 3D collection. Seems to be a real Fantasy Zone rom with new arrangement ;) Unfortunately roms are compressed... maybe some smart members can extract these datas. - extracted files and a fresh rom .zip downloaded from a rom site are very very close in size (diff from ~1KB to 3KB) - Every rom have a "mdf" ascii header (do not know what is it) 6D 64 66 00 00 00 04 00 "04" value seems to be related to rom size 02 = 128k (maze walker) 04 = 256k (fz 1, fz 2) - real FZ rom is 128kb this one seems bigger 08 = 512k (sonic MD, altered beast MD) ... I've added some other roms (sms) from the collection for testing/comparison purpose. 
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Posted: Sun Dec 10, 2017 9:34 pm
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| A quick Google for "MDF compression" lead me to this: https://gbatemp.net/threads/the-general-vc-rom-injection-thread-nes-gb-c-a-etc.3... but I'm not using a real computer to try it... | |
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Posted: Sun Dec 10, 2017 10:19 pm
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Very nice find Maxim !
So I've extracted Fantasy Zone (with old and new opll), Fantasy 2 and Maze Walker unfortunately (for us) only Fantasy Zone 2 and Maze Walker are working... - Fantasy Zone with old OPLL, i can see Sega Mark III logo but can't go further (loop) - Fantasy Zone with new OPLL : black screen. TMR SEGA is present at 0x7FF0 like a normal SMS rom. edit. Maze Walker sprites are corrupted.... |
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Posted: Mon Dec 11, 2017 5:23 am
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"FantasyZone2_J" is an exact copy of the Japanese release of Fantasy Zone II (CRC32: c722fb42).
"MazeWalker_patch" is the same size (128KB) as the released version of Maze Walker, but 1081 bytes differ between the two ROMs. "FZ1_OLD_OPLL_OB" is, as predicted, 256KB in size. It is made up of the original 128KB Japanese [v0] release of Fantasy Zone, with 810 bytes changed, followed by ~32KB of new code and data, then 96KB of zeros. "FZ1_NEW_OPLL_OB" is similar - it is an expanded version of the Western [v2] release of Fantasy Zone, with 1760 bytes changed (including a block of 1088 $ff => $00). Except for 9 bytes, the new second half of the ROM is identical to the "OLD" version. In all three cases, many of the changed bytes are genuine patches, but some are corruptions. As mentioned above, these cause sprite errors in Maze Walker, and prevent both Fantasy Zone versions from getting past the "Sega Mark III" logo. However, if "FZ1_NEW_OPLL_OB" is patched to correct ROM[$009cb] from $c3 to $d9, a corrupted version of the title screen will appear. By further patching ROM[$009ea] $c1 => $ed and ROM[$009ec] $fb => $e1, the logo will display correctly... My first thought was that these corruptions were being caused by flaws in the decompressor, but in fact all it does is "unobfuscate" the MDF file and pass the result to zlib to decompress. If the "unobfuscation" is flawed, I would expect zlib decompression to fail. So, are the corrupted bytes intentional, to prevent the ROMs being used separately from the 3DS compilation? That would explain why, for Fantasy Zone, they are concentrated around the code for the title screen... @ichigobankai: Would you be able to also post the Mega Drive files, so we have a bit more data? Thanks. |
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Posted: Mon Dec 11, 2017 7:26 am
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Note that these games are generally patched to remove lawsuit-inducing things like flashing and the use of the red cross image for health items: http://www.smspower.org/Development/NintendoWiiVirtualConsoleTitles#Patches so I'd expect some of that, but what you describe seems worse that that. The alternative is some emulation hooks for enhanced behaviour which collide with something on a regular emulator.
@RetroSpark: it may be the same deal with the games at http://www.smspower.org/forums/11109-DumpingWiiVCSMSTitles which I'm afraid I've never found time to look at yet. |
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Posted: Mon Dec 11, 2017 10:16 am
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@RetroSpark
Md roms ;) |
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