NAND FLASH NAND flash also uses floating-gate transistors, but they are connected in a way that resembles a NAND gate:  several transistors are connected in series, and the bit line is pulled low only if all the word lines are pulled high (above the transistors' VT).  These groups are then connected via some additional transistors to a NOR-style bit line array in the same way  ​that single transistors are linked in NOR flash.

Electrically Erasable Programmable read only memory（EEOROM） stands for electrically erasable programmable read-only memory and is a type of non-volatile memory used in computers and other electronic devices to store relatively small amounts of data but allowing individual bytes to be erased and reprogrammed. Unlike most other kinds of non-volatile memory, an EEPROM typically allows bytes to be read, erased, and re-written individually.

SPI NAND FLASH NOR-based flash has long erase and write times,  but provides full address and data buses, allowing random access to any memory location.  This makes it a suitable replacement for older read-only memory (ROM) chips, which are used to store program code that rarely needs to be updated,

SPI NOR FLASH NOR-based flash has long erase and write times,  but provides full address and data buses, allowing random access to any memory location.  This makes it a suitable replacement for older read-only memory (ROM) chips, which are used to store program code that rarely needs to be updated,