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PostPosted: Fri Jul 06, 2018 8:01 pm 
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Great Hierophant wrote:
One curious thing however is that Rocket Games would display "ROCKET®", not "Nintendo®" on the bootup screen. The GBC checks some of these bytes to ensure that your ROM was displaying the correct name. Rocket Games presumably found a way to bypass the check, but when you replace the logo, the games work but now display Nintendo®.
BennVenn's analysis of Datel's Game Boy Modem indicated that the logo was stored in the MBC itself, and the MBC knows when to switch between the external ROM (for the desired logo) and the internal ROM (for the TMSS circumvention).

Unfortunately, BennVenn's apparently taken down his old analysis pages.


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PostPosted: Fri Jul 06, 2018 9:42 pm 
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lidnariq wrote:
Great Hierophant wrote:
One curious thing however is that Rocket Games would display "ROCKET®", not "Nintendo®" on the bootup screen. The GBC checks some of these bytes to ensure that your ROM was displaying the correct name. Rocket Games presumably found a way to bypass the check, but when you replace the logo, the games work but now display Nintendo®.
BennVenn's analysis of Datel's Game Boy Modem indicated that the logo was stored in the MBC itself, and the MBC knows when to switch between the external ROM (for the desired logo) and the internal ROM (for the TMSS circumvention).

Unfortunately, BennVenn's apparently taken down his old analysis pages.


Fortunately the Internet Archive has saved that page : https://web.archive.org/web/20150106134 ... l_MBC1.htm

Unfortunately it looks like someone is going to have to get out the logic analyzer to figure out what the Datel chip does. For the Shark MX, the extra features make sense, but for these simple games, its overkill. Moreover, I think the use of the pure Nintendo logo would have been covered by Sega v. Accolade.

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PostPosted: Wed Jul 25, 2018 12:10 pm 
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Here is an iNES-like mapper scheme which could be useful for unlicensed games and licensed games which cannot be detected by internal header alone : http://hhug.me/gbx/1.0

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PostPosted: Thu Aug 30, 2018 1:15 pm 
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Great Hierophant wrote:
I believe one of the first things that all known MMM01 carts do when they are booted up is to write to the multiplexer bit in the Mode Register. This switches control from the first 32KB bank to the last 32KB bank by outputting ROM A19-20 to CPU A13-A14. I think this is why an emulator like bgb needs the multicart menu at the beginning of the ROM, [...].


Actually, not quite. I forgot to highlight a crucial detail on the wiki page... In general the VHDL code should describe the complete behavior and the text is kind of supplementary: in unmapped mode, the high-order ROM address lines are all forced to 1 regardless of the actual register contents. That's why the last two 16kB ROM banks need to contain the menu. And because BGB doesn't know that before it inspected the header, it needs the menu up front.

The multiplex bit part is weird, because the additional #WE bit for the MBC1 mode seems pretty useless, unless the multiplex would be able to switch with the MBC mode somehow :-/


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PostPosted: Sat Sep 15, 2018 6:59 pm 
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I have attached the latest version of the List. I observe that bgb v1.5.7 can run all but three of the licensed mappers, even if it cannot do much with the Camera and the Sonar. I don't know of any emulator that can touch the Mani 74'161, MCB6 or TAMA5.


Attachments:
Unusual & Unlicensed GB & GBC.ods [21.69 KiB]
Downloaded 3 times

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PostPosted: Sun Sep 16, 2018 9:20 am 
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Great Hierophant wrote:
I don't know of any emulator that can touch the Mani 74'161, MCB6 or TAMA5.


KiGB, higan, mGBA, and GBE+ can all emulate the MBC6, at least enough to play the only game that uses it (Net de Get: Minigame @ 100). The Flash chip is only used for downloading games, and only GBE+ currently emulates enough of GB Mobile Adapter + the download servers to get that far. Flash itself isn't emulated, but I can get Flash related error screens as it concerns the downloads. At any rate, the MBC6 is partially (mostly) emulated.

higan and mGBA (and to some extent, even VBA-M) support the TAMA5 as well. I don't believe the RTC is emulated just yet though.


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