An inkjet printer comprising: a printhead with a plurality of printhead IC's, each having an array of nozzles for ejecting drops of printing fluid, and drive circuitry for driving the array of nozzles;a print engine controller for sending print data to the printhead IC's; an interface for electrical communication between the print engine controller and the printhead IC's; wherein, all the printhead IC's have a common initial address except one printhead IC at the end of the printhead, the exception having a different address such that the print engine controller sends a first broadcast instruction to any printhead IC's having the different address, the first broadcast instruction instructing the printhead IC having the different address to change its address to a first unique address, the printhead IC's being interconnected such that when the exception has undated its address, the address of the adjacent printhead IC changes to the different address so that a second broadcast command changes the write address to a second unique address and so on until all the printhead IC's have unique addresses provided by the PEC.