FW21555BB [INTEL]

The Intel 21555 is a non-transparent PCI-to-PCI bridge designed for embedded and intelligent I/O applications. It features a 64-bit primary interface and a 64-bit secondary interface with 66-MHz capability, operating at 3.3 V with 5.0-V tolerant I/O. The device supports I2O message unit, doorbell registers for interrupts, and various buffering mechanisms for posted writes and read data. It enables independent configuration and control of local subsystems, acting as a gateway to intelligent subsystems and allowing a local processor to function as an intelligent I/O processor.