Compounds of the formula are disclosed which are Fab I inhibitors and are useful in the treatment of bacterial infections. The protective circuit can recopy the data in the main data space to the virtual data space in the case that the data stored in the virtual data space are corrupted. For example, when the semiconductor memory device includes four memory block areas, one of two memory block areas simultaneously selected is connected to the first power source line, and the other is connected to the second power source line.