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Since its debut in late 1994, the Sega Channel remains one of the most fascinating footnotes of video game history. Essentially, the system had two components: a hardware cartridge that a customer plugged into his or her Sega Genesis, and a premium subscription cable TV service (usually $14.95 a month) that provided a selection of games the customer could download.
Games, when downloaded, were saved temporarily to DRAM in the cartridge (which lost its contents when the system was powered off), and the customer could download up to 50 games a month. The service also provided news about video game releases in the form of text displayed on the screen. The information transfer was one-way, however, so Sega Channel could not provide truly interactive online content.
When news of the Sega Channel first hit, I called my local cable company as the ad suggests. Unfortunately, we never received Sega Channel service in our area, so I didn't get to try it out myself.
[ From Electronic Gaming Monthly, September 1995, p.39 ]