Guide: melonDS
melonDS Links:
Does MelonDS require BIOS or Firmware?
Yes,
The firmware can come in three flavors:
DSi/3DS DS-mode firmware: 128KB
regular DS firmware: 256KB
iQue DS firmware: 512KB
DS Emulation
bios9.bin - 4KB - ARM9 BIOS
bios7.bin - 16KB - ARM7 BIOS
firmware.bin - 128/256/512KB - firmware dump
DSi Emulation
DSi ARM9 BIOS: 64KB
DSi ARM7 BIOS: 64KB
DSi Firmware: 128KB
DSi NAND image: ~240MB
Where to put the games
NDS games should be put under the retrodeck/roms/nds/ directory.