A print engine is provided for a printer unit. The print engine includes a cradle unit and a replaceable cartridge unit received within the cradle unit in a releasable manner. The print engine further includes print media transport means which can transport print media. The cartridge unit includes a body. An ink storage module assembly includes a plurality of ink storage modules and is configured to be received in the body from one side. A printhead assembly is configured to be mounted to the body at an opposite side and is configured to print upon the transported print media.