System Management Bus

Also found in: Acronyms, Wikipedia.

System Management Bus

(hardware, protocol)
(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.

SMBus website.

Software to interrogate a SMB motherboard.

SMB devices, Part 8 Kernel Mode Driver Design Guide, Win2000 DDK.
This article is provided by FOLDOC - Free Online Dictionary of Computing (


(System Management BUS) An interface between the CPU and computer system components used for low-speed system management communications. Designed by Intel and introduced on its Xeon chips, SMBus is used among other things to send charging requirements to the CPU from the battery. SMBus includes a Processor Information ROM (PIROM) that contains data about the processor and an empty EEPROM that can be used by manufacturers and resellers to record usage and service information. For more information, visit
Copyright © 1981-2019 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.
Mentioned in ?
References in periodicals archive ?
They are also often tied into the System Management Bus (SMBus) on the node being monitored, allowing remote monitoring of on-board sensors (such as voltage, temperature, fan speed, etc.).
The linchpin of the SBS specification is the system management bus. This SMBus allows for bi-directional communication between the host and other devices on the bus, as well as between devices.
The FET bus switches can also be used for isolation or expansion in system management bus (SMBus) applications.

Full browser ?