The J-Cart is a customized Mega Drive / Genesis video game cartridge that incorporated additional controller ports into the game cartridge.  The J-Cart was developed by Codemasters for Sega’s 16-bit console to expand upon the console’s capabilities by adding two additional controller ports.

Codemasters became very familiar with the Mega Drive / Genesis console while developing the Game Genie.  Since the studio was familiar with the hardware design of the console from their experience with creating the Game Genie, they utilized their knowledge to improve upon the standard Sega Genesis / Mega Drive cartridge with the introduction of the J-Cart.

By incorporating two DE-9 connectors into the game cartridge effectively allowed the development studio to create four player games for the Mega Drive / Genesis without the need of consumers having to purchase any additional hardware.  While the idea of expanding a console’s controller availability by adding additional controller ports was not a new concept it was however the first time it was done by using a standard video game cartridge.