A thermal printer is provided which can operate at high speeds either as a direct thermal printer or a thermal transfer printer. The thermal printer includes a frame, a front door assembly pivotally connected to the frame and having a thermal head secured thereto. The front door assembly positions the thermal head to facilitate recording of information on a recording medium when the door is closed as well as dissipating heat generated by the thermal print head. A platen roller is positioned within the frame which conveys the recording medium between the thermal head and the platen roller. The thermal printer also provides interference shielding which maintains security of printed data. The thermal printer is also configured to allow operation in a rigorous environment.