Not to be confused with PCI Express, PCI-X is a high performance bus designed to meet the increased I/O demands of technologies such as Fibre Channel, Gigabit Ethernet and Ultra3 SCSI. PCI-X is most often used in servers and was first developed by IBM, HP, and Compaq in 1998 and include the below features.
- Up to 133 MHz bus speed
- 64-Bit bandwidth
- 1 GB/sec throughput
- More efficient bus operation for easier interface.
- Split transactions allows an indicator device to make only one data request and relinquish the bus, instead of constantly needing to poll the bus for a response.
- Byte count that enables indicator to specify, in advance, the specific number of bytes requested, eliminating the inefficiency of speculative prefetches.
- Backward compatibility
Note: With the introduction of PCI Express, PCI-X is not as commonly found or used today.