A reduced keyboard system for the Japanese language which uses word-level disambiguation of entered keystroke sequences, and which enables the user to select the desired interpretation of an ambiguous input key sequence as kana, and then select the desired textual interpretation associated with the selected kana interpretation. The drive element is adjusted to a pre-definable minimum temperature and a pre-settable minimum temperature is maintained. One embodiment of the system of this invention comprises a computer-readable medium containing a plurality of instructions embodying the above method. The second direction is perpendicular to the first direction. Taper surfaces are formed in both side portions of the roller and are mounted on taper surfaces formed in the step portions in the lower rail and downward inclined toward a center in a width direction. Additionally, the structure includes a first isolation structure extending through an entire thickness of the substrate and surrounding the region and a second isolation structure extending through the entire thickness of the substrate and surrounding the region.