The invention may be embodied as a playing surface. The controller is configured to execute a write operation on the memory cells such that user data are written in at least one of the plural bits of data and prescribed data are written in the remaining bits of the plural bits of data. According to such a constitution, higher degree of vacuum and the ion transmission efficiency are maintained without increasing the length of the vacuum chamber. The liquid delivery unit delivers a collection liquid into the cyclone in a non-continuous fashion. If it is, a heater is turned on until the ice and snow are removed. The front region of the first chain link is connected to the rear region of the second chain link pivotably about a pivoting axis that extends perpendicular to the longitudinal axes of the chain links, such that it can be pivoted leftward and rightward referred to the first longitudinal axis up to a maximum pivoting angle.