Multiple save RAM? - NESdev BBS

Multiple save RAM?
by arfink on 2010-04-07 (#59800)

I'm working on a development cartridge and want to be able to put multiple saves on the cartridge. It'd be MMC1, and my thought it to use a bigger SRAM than needed and take the leftover more-significant bit lines and tie them to a DIP switch to be able to switch between save data banks.

I'm not the most experienced hardware hacker, but it seems to me this would work OK, so long as you didn't mess with the switches while the NES was powered on.

by Memblers on 2010-04-07 (#59801)

Sure, that would work. If you have any bankswitching outputs left over from the MMC1 you could use those too, but I guess those aren't available?

by tepples on 2010-04-07 (#59803)

Nintendo already done it: SOROM and SXROM.

by arfink on 2010-04-07 (#59807)

Thanks. And BTW Tepples, this isn't just for any RAM, but for the battery backup RAM, and I don't intend to modify the original ROM(s) for this purpose. Though that would be kinda cool.