Note that this requires specially-modified controllers; normal NES/Famicom controllers will not work. Press and hold Left + Right on the second controller, then press Reset. The screen will be white. It will initialize the SRAM and then wait for the memory dump cheat to be activated. If not, it just stays there, infinitely hung.
Memory Dump
Note that this requires specially-modified controllers; normal NES/Famicom controllers will not work. Any time during the game, press every button both on the first controller and the second controller at the same time. This dumps the memory addresses $0000 - $01FF and $0400 - $04FF to the save-RAM before going into an infinite loop/game hang.
Test Save-RAM
Note that this requires specially-modified controllers; normal NES/Famicom controllers will not work. Press and hold Up + Down on the second controller, then press Reset. The screen will be blue if SRAM is initialized with the other cheat here. Otherwise it will be red. Then the game will wait for the memory dumping cheat; if not, game hangs.