2P versus 4P. How does it know?
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I'm curious how Retropie knows if a mame game is 2P or 4P? I thought it was based on the rom itself, but I don't think that's the case. For example, TMNT the Arcade game. I have both the 2P and 4P roms. tmnt2.zip is the 4-player version. tmnt22pu.zip is the 2-player version. When launched, both play their respective 4P or 2P modes.
That being said, if I rename tmnt22pu.zip to tmnt2.zip and launch, it plays 4P. I can get the correct version running, but just overly curious where this setting is located if not the actual rom? And it's not in the mame dipswitch menu either.
Thanks.
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@Retro-Arcade-Fan if your romset of tmnt22pu.zip is a 'merged' romset, it will effectively contain the files for every single version of tmnt2, and MAME will load up the appropriate files based on the filename used.
note that sometimes the player selection may be in the service menu rather than the dipswitches. however sometimes it's not configurable and is separate rom configurations (which would seem to be the case here)
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@dankcushions That's interesting, thank you for explaining it. One last question, again out of curiosity. Where does MAME store that file-name information? I'd love to know the differences of the individual rom file names for the same games.
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@Retro-Arcade-Fan no probs! it's in the driver code for the driver for that game/arcade system. for example, here's the name and file checksums that mame2010 is looking for for tmnt22pu: https://github.com/libretro/mame2010-libretro/blob/932e6f2c4f13b67b29ab33428a4037dee9a236a8/src/mame/drivers/tmnt.c#L3605-L3632
and here's all the variants of tmnt2 in mame2010: https://github.com/libretro/mame2010-libretro/blob/932e6f2c4f13b67b29ab33428a4037dee9a236a8/src/mame/drivers/tmnt.c#L4359-L4362 - note that the 5th parameter, the machine config, are all variants of sunset riders. this basically means that TMNT2 uses the same board as the sunset riders cabinet, just different code. fun!
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@Retro-Arcade-Fan said in 2P versus 4P. How does it know?:
For example, TMNT the Arcade game. I have both the 2P and 4P roms. tmnt2.zip is the 4-player version. tmnt22pu.zip is the 2-player version. When launched, both play their respective 4P or 2P modes.
Fun fact:
There are two different TMNT arcade games.
The original is tmnt.zip or tmnt2p.zip (I think).
The tmnt2.zip and tmnt22pu.zip should both be the second game, Turtles in Time. -
@dankcushions That really is interesting. Never knew that information was hidden so far below. Thanks again!
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