 Each NOR flash cell is larger than a NAND flash cell 10 F2 vs 4 F2 even when using exactly the same semiconductor device fabrication and so each transistor, contact, etc.is exactly the same size because NOR flash cells require a separate metal contact for each cell.When NOR flash was developed, it was envisioned as a more economical and conveniently rewritable ROM than contemporary EPROM and EEPROM memories.