SPD EEPROMs also respond to I²C addresses 0x30–0x37 if they have not been write protected, and an extension (TSE series) uses addresses 0x18–0x1F to access an optional on-chip temperature sensor. All those values are seven-bit I²C addresses formed by a Device Type Identifier Code prefix (DTIC) with SA0-2: to read (1100) from slot 3, one uses codice_1. With a final R/W bit it forms the 8-bit Device Select Code. Note that the semantics of slot-id is different for write-protection operations: for them they can be not passed by the SA pins at all.