Hey,
Is it just as simple as adding the battery to the spot on the PCB to make a metroid PCB use the battery to make say FF2e or is there more to it?
The board may not have actual SRAM on it. I'm not sure but just because a game has WRAM, doesn't mean it's the type of RAM known as SRAM which is used with a battery to always maintain power. So even if a battery power supply were present the RAM might not be the right type. Also if the board wasn't mean for a battery it's going to be messy adding one I would think. Basically I would say find another board for whatever you are doing. RetroZone (retrousb.com) sells a MMC1 repro board that is brand new and will support whatever MMC1 needs you have and you won't destroy any NES games.
It's as simple as adding battery, resistors and diodes where there is empty slots for them. Unfotrunately there is no battery with the dimentions that matches the one in Nintendo games in the market, so you'll have to be tricky to make one hold on the board and make reliable contact.
MottZilla wrote:
The board may not have actual SRAM on it. I'm not sure but just because a game has WRAM, doesn't mean it's the type of RAM known as SRAM which is used with a battery to always maintain power.
The boards are built to take a standard 6264 SRAM. There are two kinds of RAM that can do that: SRAM and PSRAM. PSRAM is DRAM with a controller that makes it looks like SRAM to the host system. Some PSRAMs have a battery-backed "standby mode" that refreshes the RAM automatically while drawing reduced power; others don't.
So are you aware if NES games that don't need to battery back their RAM use PSRAM rather than SRAM? It just seemed to me that they might have gone with a lower cost option when they didn't need the battery backed feature.