Southbridge - Chip 2 of 2
PCI ISA IDE Xcelerator
Why is it called a chipset? Because in the past there were always two or more of these on a motherboard.
Some motherboards now have only one chip that performs all of the duties of the chipset, but others still
use two or more chips. Chipsets are like the motherboard's traffic cops. They direct the flow of data from
one point to another. Each chip in the chipset has its own particular job. This is chip 2 of 2 chips in
the 440BX chipset. It is called the "Southbridge." It is slightly less important than the other chip, but
out of all the motherboard's components, it is still one of the most important. Without it, the computer
could not operate. Above is a picture of the 440BX chipset. The second chip in the chipset is the
"Intel 82371EB PCI ISA IDE Xcelerator," also known as the "PIIX4E." The PIIX4E chip controls the data
traffic between the ISA slots, USB ports, IDE ports, and the BIOS. Both chips share in the task of
controlling the PCI and main memory data flow. In the diagram below you can see the data flow paths mapped
out for the chipset. Notice that the paths managed by chip 2 are shown in blue. The duties of the
Southbridge chip may vary depending on the chipset. For some chipsets, the Northbridge may control the CPU,
video, and main memory traffic, while the Southbridge chip may control the other traffic.
The paths between each component are referred to as "buses." Buses are simply the paths, or wires,
that connect one component to another. The chips in the chipset are referred to as bridges, because
they bridge the components together and ensure that the data flow is directed to the proper place.
The better chipsets are those that can handle data the fastest and most efficiently. Below is a
picture of both of the chipsets on the motherboard.