Abstract: An operation unit for a portable device is provided. The operation unit includes a display panel with a display area that is arranged on a body of the portable device and is adapted to electrically display arbitrary information, a plurality of operation buttons that are arranged in a vicinity of the display panel on the body of the portable device, a plurality of fixed lines, each of which is extended from each of the plurality of operation buttons to the display area of the display panel, a display controlling system that is adapted to control an operation of the portable device. The display controlling system displays function indexes, each of which indicates a function assigned to one of the plurality of the operation buttons based on an operation mode that the device is in so that each of the function indexes is displayed in an independent area on the display panel.

Abstract: A data file arranged in one-to-one correspondence with one unit, and a connection definition table, arranged in correspondence with each unit, for defining a data file of an arbitrary unit to which data is to be transmitted, are arranged. The unit processes data in its own data file, and writes the processed data in a data file defined by the connection definition table.