闪存：充电 v.s. 放电
NAND Flash — 1-bit stored by charge in a floating gate
Program 写入
Erase 擦除
Multi-level (MLC) — 2 bits/cell
Stored Bit
1
Electrons
0
Threshold Voltage
0.0 V
Erase Cycles
0
Wear Level
0%
Cell Worn Out! Residual charge remains. Bit read errors likely.