(SMBus, SMB) A simple two-wire bus used for communication with low-bandwidth devices on a motherboard, especially power related chips such as a laptop's rechargeable battery subsystem (see Smart Battery Data). Other devices might include temperature sensors and lid switches. A device can provide manufacturer information, indicate its model/part number, save its state for a suspend event, report different types of errors, accept control parameters, and return status. The SMB is generally not user configurable or accessible. The bus carries clock, data, and instructions and is based on Philip's I2C serial bus protocol. Support for SMBus devices is provided on Windows 2000. Windows 98 does not support such devices. The PIIX4 chipset provides SMBus functionality. Vendors using SMBus would be required to pay royalties.