The BR9080 and BR9016 series are serial EEPROMs that can be connected directly to a serial port and can be erased and written electrically. Writing and reading is performed in word units, using four types of operation commands. Communication occurs though CS, SK, DI, and DO pins, WC pin control is used to initiate a write disabled state, enabling these EEPROMs to be used as one-time ROMs. During writing, operation is checked via the internal status check.