Source : Free On-Line Dictionary of Computing

Sega Genesis/MegaDrive
     
         A {games console} made by {SEGA}.
     
        The Genesis used a {Z80} [or a clone?] for its sound
        generator.  This made the Genesis compatible with {Sega Master
        System} games through a device called a "Power Base Converter"
        which basically shut down the Genesis/MegaDrive's {68000}
        {CPU} and made the Z80 the CPU.
     
        (2003-07-29)