The NAND memory chip is based on memory cells (cell, cells) that must be able to retain their value of 1 or 0 (one bit of user data) even without power. The memory cell is technologically based on a transistor with a floating gate. The cell value is stored in the floating gate, which is isolated by an oxide insulating layer. The floating gate is able to retain its value precisely because of the oxide insulating layer. However, with each charge and discharge (write and erase/reset), the oxide insulating layer gradually loses its insulating properties. After a certain number of charge and discharge cycles, the oxide insulating layer ceases to perform its function and the memory cell fails.