Flash memory is a long-life non-volatile memory (the stored data information can still be maintained in the event of a power failure). Data deletion is not in a single byte unit but in a fixed area. Block as a unit (Note: NOR Flash is byte storage.) Flash memory (sometimes called flash RAM) is a non-volatile memory with constant power supply, which can be stored in a storage unit called a block. Delete and adapt. Flash memory is a variant of electrically erasable programmable read-only memory (EEPROM). The difference between EEPROM and flash memory is that it deletes and rewrites at the byte level, so that the update speed of EEPROM is slower than that of flash memory. Flash memory is usually used to store control codes, such as the basic input output system (BIOS) in a personal computer. When the input/output system needs to be changed (rewritten), the flash memory can be written in blocks (rather than bytes), so that the flash memory can be updated more easily.