what are the different models of this product?
Two preivious models developed by Sega , and the Genesis CDX,  X'Eye,  Wondermega and others.
Sega CD
 Genesis CDX (Multi-Mega in Europe). This console was a combination of the Genesis and Sega CD in one unit and initially retailed at US$399. Unique to this model was its additional functionality as a portable compact disc player.

Three additional system models were created by other electronics companies. Working with Sega, JVC released the Wondermega on April 1, 1992, in Japan, at an initial retail price of ¥82,800 (or US$620). The system was later redesigned by JVC and released as the X'Eye
what is 'sega cd'? A  CD-ROM accessory for the Mega Drive/Genesis . which company manufactured them? Sega. name a few electronic parts of this product. The CPU is a Motorola 68000 processor,a Backup RAM cartridge, RCA pin jacks, etc. when was this product first time sold in the market? It was released in Japan on December 12, 1991.
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Sega CD [SEP] Variations
Three additional system models were created by other electronics companies. Working with Sega, JVC released the Wondermega on April 1, 1992, in Japan, at an initial retail price of ¥82,800 (or US$620). The system was later redesigned by JVC and released as the X'Eye in North America in September 1994. Designed by JVC to be a Genesis and Sega CD combination with high-quality audio, the Wondermega's high price kept it out of the hands of average consumers. Likewise was the case with the Pioneer LaserActive, which was also an add-on that required an attachment developed by Sega, known as the Mega-LD pack, in order to play Genesis and Sega CD games.