Intel offers both transparent and non-transparent PCI bridges, as well as a PCI-X transparent bridge with opaque memory mode for semi-transparent operation. Both product lines allow designers to add more PCI/PCI-X devices or more PCI/PCI-X option card slots than a single PCI bus can support. However, non-transparent bridges differ from standard, transparent PCI-to-PCI bridges by allowing independent mapping of primary and secondary bus address spaces, a key benefit when local devices require private memory maps.
