http://haze.mameworld.info/2006/07/28/genesis/
This is exactly the reason why pirate originals must be preserved.One of the most entertaining parts of emulating an already emulated platform is trying to find out why certain games that run on the said platform don?t work in the most popular emulators.
One such game is the Genesis game Squirrel King, It?s an unlicensed game, and in both Kega and Gens you simply fall through the floor as soon as the level begins. The graphics on the player select screen are also corrupt in both emulators.
The falling through the floor problem actually appears to be some kind of additional protection device in the cart. The game writes a value to 0?400002 (just above the normal ROM space) and expects to read a value back from 0?400000. Returning the value just written is enough to prevent the character from falling through the floor, making the game playable. The corruption on the select screen remains a mystery. The game doesn?t appear to do any fancy DMA tricks so a closer look at what is in Video RAM may be needed.
In no other game, rewriting value from 0?400002 to 0?400000 appeared important to emulator authors, tho the hardware behave like that. If such pirate originals weren't preserved, such feature from hardware would be lost forever. Pirate originals are needed for a more accurate emulation.
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Re: Genesis \ FluBBa on 30th July 2006, 11:19 wrote:
If I understand this correctly the problem has nothing to do with the actual Genesis hardware but the hardware in the cartridge.The falling through the floor problem actually appears to be some kind of additional protection device in the cart. The game writes a value to 0?400002 (just above the normal ROM space) and expects to read a value back from 0?400000.
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Re: Genesis \ Yakushi~Kabuto on 30th July 2006, 11:43 wrote:
You might be right but as I read it the genesis hardware write back to 0?400000 any value it reads at 0?400002. An additional protection device can be any kind of software protection, I really don't see it as an hardware protection, especially for a cheap pirate xD
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Re: Genesis \ alcoatjez on 31st July 2006, 09:18 wrote:
I'm with Cobra on this one. I think there are many more pirates which use functions of the consoles not used in with originals.
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Re: Genesis \ FluBBa on 1st August 2006, 13:39 wrote:
Yeah, maybe Haze is wrong saying the protection is in the cart and not in the Genesis itself.
I'm not saying you shouldn't put Pirate originals in your dats ('cause that I'm all for).