Firecore is a system-on-a-chip clone hardware based on the Sega Genesis/Mega Drive system, originating in the late 2000s. It is infamous for its poor sound, which is lower-pitched and in a different key than a standard Genesis. It can also load ROMs from an SD card if the console includes a slot for one. Many of the recent Genesis bootlegs (such as those made by BMB) are designed with Firecore architecture in mind, and do not play properly on the original console(s).
The majority of (post-2010) bootleg Genesis clones use Firecore, but it was also featured on official Sega systems by AtGames, which was met with lots of criticism (mainly due to its sound emulation). Sega eventually ended their partnership with AtGames due to the increasing negative backlash. A similar hardware is used in some Sega-licensed systems by Tectoy, but the sound is significantly more accurate.