Models
The Mega Drive.
Released on 29/10/1988 in Japan.
The Genesis.
Released on 14/08/1989 in America.
The Mega Drive.
Released on 09/1990 in Europe.
Motherboard
Motherboard
Showing the Japanese 'VA0' revision.
Notice the unusual daughterboard on top of the VDP used to fix post-manufacturing glitches (properly corrected in later revisions).
Motherboard with important parts labelled
Diagram
Main architecture diagram