PCI stands for Peripheral Component Interconnect. It is developed by INTEL in 1990. It is a 32-bit local bus which extends the processor an local bus and it can be extended to 64-bit when needed. It delivers better system performance for high speed Input/Output sub-system.

PCI is designed to meet economically the I/O requirements of modern system. It requires very few chip to implement & support other buses attached to the PCI bus. It is a high performance connection between the motherboard component and expansion board of a system. The PCI buses imply a 124 pins. It specifies for two connections, 5 volt connection and 3.3 Volt lower power connection. It is designed to support a variety of microprocessor based configuration, including both single and multiple processor system.

• PCI Buses of a Single Processor System : A combine DRAM controller and bridge to the PCI bus tight coupling with the processor and ability to delivered data at the high speed. The bridge act as a data buffer so that the speed of the PCI bus may differ from that of the processor I/O capability.

• PCI Buses of a Multi Processor System : A multiprocessor system is also called as 'Typical Server System'. The processor system bus is connected with host bridge to which one or more PCI configuration is connected. The system bus supports the processor cache unit, main memory and the PCI bridge. Host bridge keeps the PCI independent of the processor speed and provides the ability to review and ability to deliver data at rapidly.