When you see a file named nand.bin in the context of melonDS, it is a bit-for-bit dump of that internal memory. It is the "soul" of a specific Nintendo DSi console.
In summary, the nand.bin file is an essential component of MelonDS, as it allows the emulator to simulate the NAND memory of a real NDS console. Users need to obtain a valid nand.bin file to use MelonDS, and incorrect or missing files can cause issues with the emulator. nand.bin melonds
Under , browse and select your nand.bin file. When you see a file named nand