Because the technique of forced oscillations requires little co-operation from the patient it is frequently employed in the diagnosis and treatment of respiratory diseases. To make routine use of this method possible, by medical researchers as well as clinicians, a special-purpose computer has been developed to determine those parameters of interest. The total respiratory resistance and the phase angle of the respiratory system are read out directly in one of three possible ways; over each cycle of imposed oscillation, averaged over inspiration or expiration, or averaged over several breaths. The frequency of imposed oscillation is variable from 4–16 Hz. Over this band of frequencies, resistance calculations have a dynamic range of 20∶1, while phase angle is measured between ±90°.