I2C(also IIC; the "2" is superscripted) Inter-Integrated Circuit Bus -- A moderate-speed serial communications bus originally invented by Philips in the early 1980s for consumer-electronics applications, such as inter-chip communication in a television set or high-end stereo. The I2C bus has recently appeared on PCs in video capture boards and similar devices, as well as (surprisingly) SDRAM DIMMs (for the on-board serial EEPROM). The ACCESS.bus is a derivative of the I2C bus which forms the physical layer of the Universal Serial Bus. Similary, the SMBus (System Management Bus) also uses I2C as its physical layer. 18h - SMBus(System Management Bus) A derivative of the I2C bus used for communication between various components of a computer, such as smart batteries and their chargers. In contrast to I2C, SMBus specifies fixed voltage levels (instead of relative to the power supply voltage) and a 10 KHz minimum clock rate (I2C minimum is 0). SMBus also specifies several timings which are not required by I2C. See also I2C, ACCESS.bus. - Alert Response Address Access: Read-Only Desc: used to query the SMBus(System Management Bus) A derivative of the I2C bus used for communication between various components of a computer, such as smart batteries and their chargers. In contrast to I2C, SMBus specifies fixed voltage levels (instead of relative to the power supply voltage) and a 10 KHz minimum clock rate (I2C minimum is 0). SMBus also specifies several timings which are not required by I2C. See also I2C, ACCESS.bus. for the address of the device sending an alert; one byte is returned, containing the device's address in the upper seven bits (bit 0 is undefined)