A cartridge chip for use with a first type of imaging cartridge and a second type of imaging cartridge comprises a controller and a resistive element connected between the controller and a reference potential, the cartridge chip adapted for operation in a first mode of operation compatible with the first type of imaging cartridge when the controller detects the reference potential through the resistive element, the cartridge chip adapted for operation in a second mode of operation compatible with the second type of imaging cartridge when the controller cannot detect the reference potential through the resistive element.