The Sega Multi Mega, or Sega CDX in North America, was a variation of the Mega Drive / Genesis and Sega CD / Mega CD. It was released in 1994, before the Sega 32X. It retailed for £350 in Europe/UK, and $399 in North America.
The console was a combination of the Sega Mega Drive/Genesis, with a cartridge slot in the top-back of the console, and Sega CD/Mega CD games, with a frontloading flip-top CD drive in the top-front. It could be powered by two AA batteries, which would allow the owner to listen to audio CDs on the go, using the stereo headphone port of the Multi Mega. It could also be powered by mains electricity, and use a TV lead to play on the television.
 Failure Reasons
The Mega CD/Sega CD wasn't massively popular, and nether was the Multi Mega/CDX. The portable CD capabilities were somewhat revolutionary, but the two AA batteries barely lasted a couple of hours. The console was released late in the Mega Drive's and Mega CD's life, and was overpriced for both systems. There were also other systems that played the combination of Mega Drive / Genesis and Sega Mega CD games, such as the JVC X'Eye, Victor Wondermega, Pioneer Laseractive Sega PAC, and a few more clones.
 32X compatibility
There is a lot of confusion of whether the Sega Mega Drive / Genesis add on, the Sega 32X, works with the CDX / Multi Mega. Sega stated in the CDX's manual that the 32X worked with the CDX. But later, a paper insert was added in stating otherwise. This was because FCC did not approve the 32X being used with the CDX. But on Multi Mega adverts, the Multi Mega system was usually shown with a 32X inserted in the cartridge slot. Despite Sega's claims that the 32X wasn't compatible, if properly connected, it will. Sega / Mega CD 32X games were also compatible with the Multi Mega.