To reduce the hardware of the graphics computer in size and reduce the cost of the hardware, the frame buffer and the main memory are united into one unit to process graphics data in the CPU. The chair frame includes two lateral frame parts. The washer member has a circular disk-like section and an engaging protrusion and is configured to be mounted in an axial direction on the handle shaft. In a preferred embodiment, the target file server maintains a hierarchy of on-line nodes off-line nodes. In articular, the method comprises the steps of monitoring the voltage across the superconductive material while the propagation current is being applied; and ceasing application of the propagation current in response to the detection of a voltage across the superconductive material which exceeds a certain threshold level. The compound for the organic EL device has an indolocarbazole structure or a structure similar thereto in the molecule wherein an aromatic group is bonded to the nitrogen atom in the indolocarbazole.