Genesis:Sega CD Model Differences

Page content & researching taken from io55.net's Genesis Add-Ons page with permission, in collaboration.

Models
''Models are arranged chronologically. There are no revisions.''

“CD (Model 1; mechanical tray)” (1992?)
The slightly less robust Sega CD, mainly in being less reliable (capacitors and the CD tray). Installs to the bottom of a Model 1 Genesis, with a front-loading drive mechanism prone to failure. The Model 1 will work with a Model 2 Genesis, but it will require expansion plates and screwing.

“CD (Model 2; top loader)” (1993-1996)
The somewhat more robust Sega CD, mainly in being more reliable (definitely CD tray, maybe capacitors). Installs to the side of a Model 2 Genesis, while being supported by both the side and bottom. The Model 2 will work with a Model 1 Genesis, but it will require expansion plates and screwing. Units with a model number ending in “A” are made in Japan, rather than China.