Methods and apparatus are disclosed for erasing memory cells in a virtual ground memory core, wherein a row decoder apparatus employs a protective voltage to wordlines of a sector of cells while concurrently providing an erase voltage to selected wordlines of the same physical sector. Decoder circuitry and methods are disclosed for selecting a memory cell sector to be erased and adjacent sectors to be protected, which may be used in single bit and dual bit memory devices, and which enable column decoder circuitry to reduce the number of sector select circuits.