IC PCI bridges are semiconductors used to expand the number of slots available on peripheral component interconnect (PCI) devices. There are three basic types: host controllers, transparent bus bridges, and nontransparent bus bridges.
PCI host controller devices act as a bridge between a processor bus and a PCI bus. These are generally built into a computer and cannot be added after the fact except using a processor-direct slot (PDS). A transparent bridge device is commonly used to extend a PCI bus beyond the physical distance allowed for a simple bus by the PCI specification. A nontransparent bridge device is often used to connect two PCI buses that are managed by separate hosts. A power-managed PCI bridge device supports an extended capabilities list, and within the capabilities list, provides the PCI power management interface registers.