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PostPosted: Sun May 15, 2016 10:40 am 
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Hey folks,

I'm trying to run these games for a long time. Searching over the internet since a few years. There isn't a single clue if anyone was able to rune these games.

It's a CD as like as video cd structure (with CDI, EXT, MPEGAV, SEGMENT, VCD folders ) with an extra NEWROM folder. The NEWROM folder has 300 .bin files which are some kind of processed NES roms. This CD comes with some old VCD player with game facility. The CD runs on thos VCD player but not on any emulator on PC. The cd title says 'NES_DISK V1'.

I've compared some .bin files with original NES roms in a hex editor. The result I see is really hopeful. Those bin files has fresh rom data without NES header and some data added before and after the rom data. I'm not a NES developer and I don't know how to modify or fix a NES file, so I may be wrong.

This topic has been discussed on many places but I did not find any solution anywhere. It's like a mystery. Can anyone solve the puzzle? I can send some of the rom files and I also have the name of those games so that you can compare to a fresh rom. I really want to play some games which I cannot find on the internet.

Cheers.
Sohan


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PostPosted: Mon May 16, 2016 6:14 am 
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That sounds pretty interesting. I'll take a look.


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PostPosted: Mon May 16, 2016 7:24 am 
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But is there anything interesting among these ROMs? I wouldn't be surprised if it was all standard multi-cart crap.


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PostPosted: Mon May 16, 2016 11:24 am 
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It looks like you can take the two-byte (big-endian) value at offset 6 and add $61C0 to get the offset where the ROM starts, but there's no clear indication of ROM size, mirroring, or mapper. On top of that, some of these ROMs have been hacked specifically for the emulator.

There wasn't anything particularly interesting in the four ROMs I looked at:

  • Contra (U) with a single byte changed, making the game crash (probably a hack for idle loop detection)
  • Ikki (J) with the copyright text removed (same as [p2] in GoodNES) and, oddly, the IRQ/BRK vector changed to match the NMI vector
  • The Little Mermaid (U) with a trainer menu and an inexplicable change to its graphics ("DISXEY", "XIXTEXDO", "PRESS START BUTTOX")
  • Rainbow Islands - The Story of Bubble Bobble 2 (J) with the copyright text removed (same as [p1] in GoodNES) and the same game-breaking one-byte idle loop detection hack as Contra


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PostPosted: Mon May 16, 2016 11:28 am 
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The ones I looked at seemed to be 52400 bytes of header (looks like MIPS machine code?), followed by the concatenation of the PRG and CHR, and then 4944 bytes of footer.

Takahashi Meijin no Boukenjima (J) had also a single byte changed (to $FB)


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PostPosted: Sat May 21, 2016 2:15 am 
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Joe wrote:
It looks like you can take the two-byte (big-endian) value at offset 6 and add $61C0 to get the offset where the ROM starts, but there's no clear indication of ROM size, mirroring, or mapper. On top of that, some of these ROMs have been hacked specifically for the emulator.

There wasn't anything particularly interesting in the four ROMs I looked at:

  • Contra (U) with a single byte changed, making the game crash (probably a hack for idle loop detection)
  • Ikki (J) with the copyright text removed (same as [p2] in GoodNES) and, oddly, the IRQ/BRK vector changed to match the NMI vector
  • The Little Mermaid (U) with a trainer menu and an inexplicable change to its graphics ("DISXEY", "XIXTEXDO", "PRESS START BUTTOX")
  • Rainbow Islands - The Story of Bubble Bobble 2 (J) with the copyright text removed (same as [p1] in GoodNES) and the same game-breaking one-byte idle loop detection hack as Contra


I'm actually really noob at this. I have no Idea how to check/modify a nes rom. But I've opened those files in a hex editor. Found a string value "Need:%" or something like this. Rom data starts after this in all of those .bin files. Also some data added at the end. So it's actually possible to get rom data from any of those .bin files. But unsure about what you say header or mapper. I really don't understand this. Is it possible to convert those .bin files to a working .NES files?


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PostPosted: Sat May 21, 2016 3:38 am 
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sohan wrote:
Is it possible to convert those .bin files to a working .NES files?

Yes, but it's not easy, and it's not possible to do it automatically (with a converter program).

The .bin file doesn't say how big the PRG or CHR ROMs are. I had to look at the data myself to try to figure out how big each part is supposed to be.

The .bin file doesn't say what kind of cartridge the game uses. There are over 100 different cartridge types, and they are not compatible with each other. The .nes file calls this the mapper number.

The game in the .bin file might use special emulator-specific hacks. Other emulators (and a real NES/Famicom) won't run the hacked game. If you don't have a copy of the original game to compare (because you don't know which game it is), you have to run the game in a debugger and try to figure out where it goes wrong.


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PostPosted: Sat May 21, 2016 9:14 am 
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Can you overwrite the PRG and CHR sections with the PRG and CHR of an appropriately sized Holy Diver Batman ROM? It'll at least print the mapper number that the emulator is assuming. And if the problem is one of finding the dividing line between PRG ROM and CHR ROM in a given ROM image, you could think of a heuristic for detecting strings of bytes that are likely to be CHR data (such as correlation among adjacent pixels of each tile when decoded).


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PostPosted: Mon May 23, 2016 9:15 am 
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If those are just standard NES ROMs with a few modifications, why even bother to get that Super VCD stuff to run in the first place? Why not take an emulator and use regular ROMs?

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PostPosted: Mon May 23, 2016 9:57 am 
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As I understand "some games which I cannot find on the internet", the collection includes some exclusive games and/or hacks thereof.


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PostPosted: Mon May 23, 2016 10:06 am 
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About hacks: Who gives a shit about hacks?

And actual exclusive games: Well, that would indeed be interesting. Which games are they? There are really games in that collection that aren't listed, for example, in GoodNES?

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PostPosted: Mon May 23, 2016 10:55 am 
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The thing is, every single game is now available on the net. But some games on that collection had their name changed. So it's hard to find those games, at least for me. Also I don't have the full list of those games. Found about half of the list here. So can't remember all of those games of that CD. That's why I opened this topic.


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PostPosted: Mon May 23, 2016 11:19 am 
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sohan wrote:
But some games on that collection had their name changed. So it's hard to find those games, at least for me.

In this case, I would suggest to simply post the title screen and one gameplay screenshot of every game that interests you and I'm sure people here will be able to tell you what's the official name of that game. In my opinion, that's better than fiddling with those ROM images.

Alternately, this video:
www.youtube.com/watch?v=JueI4bsctgQ
provides one screenshot for 2648 ROMs in 45 minutes.

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PostPosted: Fri May 27, 2016 9:34 pm 
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I still think figuring out the file format they use and the details to execute it would be of interest.

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PostPosted: Fri May 27, 2016 9:39 pm 
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zzo38 wrote:
I still think figuring out the file format they use and the details to execute it would be of interest.


If you want to see one of those roms, let me know. I can give you :)


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