A nonvolatile memory device includes a plurality of memory blocks, and a pass transistor array transmitting a plurality of drive signals to a selected memory block among the plurality of memory blocks in response to a block select signal. The locator system may be used to receive radiolocation signals, calculate location data based on the radiolocation signals, and send the current location data over a telecommunication network to a server computer. A mobile station provides information on the quality of the signal received from the base station, and the base station responds by adjusting the power allocated to that user in a shared base station signal. Moreover, since the self-propelled cleaner is designed to cause the drive mechanism provided therein to turn the body BD, it is not necessary to additionally provide a device to turn the infrared CCD sensor, thus reducing the manufacturing cost. Thereby, there is provided a simple, cheap and reliable electric starter motor capable of engaging and disengaging the idle gear and ring gear with each other and from each other without increasing the number of parts.