Abstract: A thermal demand printer for printing on media is a novel system which includes a case structure including a hinged cover panel, easily removable guide structures and media hanger, and a single central support wall to which the various components are attached. The printer includes a power supply circuit for receiving power from an external source and conditioning it for operation of the printer. An input device is provided for receiving command signals related to the operation of the printer. A control circuit for processing the command signals and generating corresponding control signals for controlling the operation of the printer and a printhead assembly for processing the control signals and generating corresponding control signals for controlling the operation of the printer are mounted in the case structure and coupled to the input device and the power supply circuit. The printhead assembly includes a printhead support structure which controls the printhead.