C.1.12.1 XB9+

The XB9+ ASIC is a buffered memory crossbar device that acts as the bridge between the six system unit buses. The six system unit buses include two processor buses, a memory data bus, a graphics bus, and two I/O buses. The XB9+ ASIC provides the following:

• Six-port crossbar

• Decoupled memory port; loading and unloading of memory data can take place in parallel with other operations

• Burst transfers operate on a doubleword of data per slice

• A total of eight two-entry first-in-first-out (FIFO) devices for read data storage

• Power-up safe buses (tristated)