Combining the advantages of conventional ISA bus technology with the high speed of local-bus PCI, the XPCI-SB backplane is based on the PICMG standard. This backplane has a secondary PCI bus in addition to the primary PCI bus by using a PCI-to-PCI bridge chip to extend the electrical capacity of the PCI bus to allow more PCI slots than a single bus. The XCPI-SB provides six PCI slots, one CPU slot, and 12 ISA slots.