Because BIOS files are copyrighted intellectual property owned by Nintendo, downloading them from third-party sites on the open web violates copyright law. The legally compliant method is to dump them directly from your physical Nintendo DSi or 3DS hardware. nds-bios-firmware directory listing - Internet Archive
The first four bytes 0x4E 0x45 0x4E 0x45 = "NENE" – could be a used by the challenge author. biosdsi9rom
An authentic system dump must exactly match its physical counterpart's storage capacity down to the byte. Altered or partial files will cause immediate boot failures. An authentic system dump must exactly match its
You will primarily encounter biosdsi9rom (or its standard name biosdsi9.bin ) in the context of these popular emulators: The DSi, while backwards compatible, has upgraded processors
The Nintendo DS had two CPUs and a specific firmware. The DSi, while backwards compatible, has upgraded processors and a completely different boot process, hence its own set of BIOS files. While some emulators might accept DSi BIOS dumps as a substitute for original DS files, the reverse is not true. A standard DS BIOS will allow you to emulate DSi-exclusive games.
CTFbios_dsi9rom_decoded_is_sanest_123
# Find printable strings strings -a biosdsi9rom.bin | less