Basics Technology .
Flash cards use flash memory chips to store and retrieve the data.
NOR NOR represents the earliest flash design. NOR devices use energy consuming hot electron injection for data writing and tunnel release for erasing. One disadvantage of NOR is that they are difficult to scale up to higher capacities. NAND use tunnel injection for writing and tunnel release for erasing, which is a power-saving technique. It offers multiblock erase and auxiliary Byte redundancy for ECC .