The printing apparatus applies a first waveform to the liquid detection sensor, and measures a second waveform output from the liquid detection sensor in response to the application of the first waveform. The present invention provides a built-in self test circuit which operates with high speed phase lock loop. The housing is provided with wheels and a handle so that the housing may be utilized in cart-like fashion. An embedded interactive link that graphically represents at least one point of interest is highlighted within the map. The abdominal section of the patient abuts against the bracing surface of the orthopedic support pillow when the patient is lying in the prone position sideways.