A heating system is disclosed, which includes a main body having a duct formed therein, an air flowing guiding member, and a heating unit. The lead frame has a frame-shaped land; a die pad for mounting the semiconductor chip; first to fourth supporters supporting the die pad so that the die pad is located in the center of the land; and first to fourth groups of lead members formed in first to fourth trapezoidal areas, the shorter bases of which face the center of the land and the longer bases of which face the sides of the land. In one embodiment, the first selection device may have a threshold voltage substantially equal to its holding voltage. The memory cell turning on generates a bit line indication that causes the digital count to be compared to a representation of the target data to be programmed in the memory cell. Adjustments are made to the measuring device based on the difference between the current measurement data and the master measurement data.