The Nintendo DSi and 3DS have expanded menus. Users who have hacked their DSi via "Memory Pit" or their 3DS with Luma3DS sometimes seek out the original DS Menu ROM to dual-boot or to launch legacy applications that require the specific ARM7 BIOS environment of the original DS phat.
A is not a retail game. Instead, it is a dump of the system firmware that controls the Nintendo DS’s main menu interface — the screen you see when you turn on a real DS with no game card inserted. nintendo ds menu rom