Comment by bitwize

Sega actually did what Nintendidn't. The Sega Genesis had a Z80 coprocessor, a video chip that was yet another extension of the TMS9918A design, and a PSG sound chip -- all just more advanced, or supplemented by other hardware, versions of components the Master System had. With an adapter add-on called the Power Base Converter, Master System games could be played on the Genesis.