Traditionally in x86 computers, the processor's primary connection to the rest of the machine was through the motherboard chipset's northbridge. The northbridge was directly responsible for communications with high-speed devices (system memory and primary expansion buses, such as PCIe, AGP, and PCI cards, being common examples) and conversely any system communication back to the processor. This connection between the processor and northbridge is commonly designated the front-side bus (FSB). Requests to resources not directly controlled by the northbridge were offloaded to the southbridge, with the northbridge being an intermediary between the processor and the southbridge. The southbridge handled "everything else", generally lower-speed peripherals and board functions (the largest being hard disk and storage connectivity) such as USB, parallel and serial communications. In 1990s and early 2000s, the interface between a northbridge and southbridge was the PCI bus.[1]