The upper left buttons is program, and The lower buttons is erase. Turn off the power (SPST switch on the left) still keeps the memory. It uses mosfets, but reality it is a mosfet with an extra oxide layer to keep the charge for memory in the middle conductive layer(Fgfet). Fgfets are used for Solid state memory, just about at least 1,000x more time the bits.
