Optim 600 Color was a console marketed in the United Kingdom in 1978 and belonging to the PC-50x family. It used interchangeable cartridges containing much of the circuitry required to generate each game, using dedicated General Instrument chips. This system made it possible to offer different types of games simply by changing the cartridge, including sports, racing and combat titles. The machine had two external joystick controllers and additional controls on the console itself.