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RoberBellie
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Making SMS/GG multicart, coment or suggestions
 Posted: Wed Jan 24, 2001 10:05 pm
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I've been drawing up a few papers and the possibility looks good. What I might do aqt this time is to make a multicart that handles either 1 Meg or 2 Meg games. At this time, 4 Meg is not on agenda because most good 4 Meg games uses battery backup and I haven't figured out how to make multibanked SRAM so each games won't fight for the save space.
Right now, I am favoring using a pair of 8M EPROMs to have up to 16 1 Meg or 8 2 Meg games and using DIP switch to select the chunk of EPROM. For excample, with 16 1 Meg games, I'd use a total of 3 switches to select block 0 through block 7, and a 4th one in connection to _CE line to enable either EPROM 1 or 2 or disable both if _CE is high. All I'd need is a pair of NAND gates to toggle the 2 EPROMs only when _CE is low and have both on high (disable mode) when _CE is high. Plus 2 spare NAND gates are left in case the EPROM I get has high to enable rather than low.
Yes, I could do this with Game Gear images but it'd have to be done via Master Gear adapter on Game Gear as SMS won't accept most GG games due to checksum, and Power Base Converter doesn't have the correct video mode. Also I wouldn't really know how to convert old game gear game to EPROM game that'd fit inside the case and have correct mapper for laqrger games.
It's still only a theory but looks very good on paper and it was tested on my relic Mac program (DigiSIM, circa 1986) to simulate some logic circuit.
I'd like to use a single 16M or even the monster sized 32M EPROM but my burner doesn't take anything that big and no adapter are available at this time. Plus those are huge, still very expensive and I don't have much details on specs.
(PS have you seen the UV window on the 32M EPROM? Almost as big as a standard 14 pin DIP chip! I can tell my old UV eraser is going to need the Alka-Seltzer after it tries to digest that monster ;-) )
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