A method and apparatus for permitting diagnostics in a PC is described. In the process for the memory cell to reading stored data by selecting specific word lines, word lines neighboring the selected word line are selected at the same time, or the two bit lines are connected at the same time to the input terminals of the sense amplifiers, thus increasing the difference in voltage between both the input terminals of the sense amplifiers. Spatial processor operation may also be optimized to operate in conjunction with orthogonal frequency division multiplexing. A conductive layer is formed on the second semiconductor layer 16 in a divided pattern that provides a segment for each photodiode and is connected to the second semiconductor layer along the an outer periphery with respect to all photodiodes. This battery case 100 includes a negative-electrode case member 115 made of an electrically conductive material and serving as a negative collector plate to which the negative electrode lead portions 123r are connected. The lower rack includes a substantially unobstructed bottom surface.