To make thin a circuit device 10 in which are incorporated a plurality of types of circuit elements 12 that differ in thickness, first conductive patterns, onto which comparatively thin circuit elements 12A are mounted, are formed thickly, and second conductive patterns 11B, onto which comparatively thick second circuit elements 12B are mounted, are formed thinly. A method, apparatus and system are configured to support a plurality of reliable communication channels using a shared send queue. A second liquid supply module including a second liquid reservoir is in fluid communication with the second printhead and provides liquid from the second liquid reservoir to the second printhead.