Abstract: A personal computer includes a built-in printer having a transport path which extends parallel to a surface of the computer housing. The transport path may extend along the entire length of the housing surface, or only partially so. Situated within the housing is a printhead which may be either fixed or movable relative to a print medium inserted into the transport path. If movable, the printhead may have one or two degrees of freedom. An arrangement of sensors, rollers, and other mechanisms may be situated into the housing to automatically move a print medium through the transport path. The personal computer may be incorporated within a system for printing a mark indicative of a stamp or private-carrier rate on an envelope inserted into the transport path. In this system, the scale may be weighed using a removable scale cartridge inserted into a communications port of the computer.