In a block which is a target of detection of flag data, a page buffer 100 reads data of memory cells 42 of each memory cell by block unit, and latches the data. A light emitting diode die is coupled to the first conductive portion. The grip has a substantially cone shaped cross-section. The second core extends along the length, is spaced a distance from the first core, and is sized and configured to provide propagation of light along the second core along the length of the cable. The threshold is one minus a guard bandwidth of the high bandwidth channel. The input device is rotatable to move the lock member from a first position to a second position, the second position defining a locked position wherein the lock member is adapted to be in contact with the engagement surface.