The Model 1 Mega Drive does require a plastic extender to 'properly' fit on the Model 1 Mega CD. You can use either system model (or the SG Mega) with either Mega CD, but the Model 2 looks small on top the Model 1 Mega CD.

The Model 1 was built around being used with a Model 1 Mega Drive and likewise for the Model 2. The Model 1, with a mechanical tray for the CD drive.

It could also be combined with the 32X to form a behemoth of a system for which only six (terrible) games were made. All this power was mostly wasted on hilariously cheesy FMV 'games' nonetheless, this system had a good number of quality games. The Mega-CD sold approximately six million units worldwide before Sega discontinued it in 1999.Known as Sega CD in the US, this was not just a CD drive for the Mega Drive: it added a faster CPU, new graphics and audio processors, and more RAM. Released in Japan in 1991, it allowed gamers to play CD-based games on the Mega Drive as well as audio CDs. The Mega Drive/Genesis also supported a number of add-on components, including the Mega-CD, known in the US as the Sega CD. Mega Drive games also received re-release as part of collector's editions for the Sony PS2 and PSP, and other systems, as well as being available for download on the Nintendo Wii Virtual Console. Games continued to be released internationally as recently as 2002. The first successful 16-bit system, the Mega Drive's 14-year lifespan places it second only to the Nintendo Game Boy. With seven distinct versions the Mega Drive has the largest number of licensed versions of any console. The Genesis could do things that the NES simply couldn't. Sega also focused attention on its better graphics, speed, and sound, especially after the release of Sonic. These efforts were often successful, as Sega marketed the Genesis as hip, cool, and edgy. In addition to porting over popular coin-op games, Sega executives worked hard to lure developers away from Nintendo. Dubbed the Genesis, this version was developed with the American market and consumer in mind. A year later, Sega released the Mega Drive in the United States. Released in 1988, the Sega Mega Drive heralded the coming of the 16-bit era and inaugurated the Console Wars of the 1990s.

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