A wireless user device includes functionality for detecting and collecting information about network hotspots in a surrounding environment before an operating system is loaded. The invoice is sent to the buyer. First group writing circuits 30a, 30c connected to even-numbered bit lines BL0, BL2 and second group writing circuits 30b, 30d connected to odd-numbered bit lines BL1, BL3 are controlled to an active state and a non-active state respectively on the basis of control signals TSE, TSO.