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Memory Controller and Bus Bridge

The Uni-N memory controller and bus bridge IC provides cost and performance benefits by combining several functions into a single IC. It contains the memory controller, the PCI bus bridge, the Ethernet and FireWire interfaces, and the AGP port.

In addition to the four buses listed in Table 2-1 , the Uni-N IC also has separate interfaces to the physical layer (PHY) ICs for Ethernet and FireWire and an I² C interface that is used for configuring the memory subsystem.

Table 2-1 Buses supported by the Uni-N IC

Name of bus	Destinations	Width of data path	Bus clock speed
60x bus	Microprocessor	64 bits	100 MHz
Memory bus	System RAM	64 bits	100 MHz
PCI bus	KeyLargo IC and Boot ROM	32 bits	33 MHz
AGP port	Graphics IC	32 bits	66 MHz

The microprocessor and the I/O controller IC are described in their own sections. The following sections describe the other subsystems that are connected to the Uni-N IC.

Memory Controller and Bus Bridge

System RAM

Boot ROM

FireWire Controller

Ethernet Controller

Video Display Subsystem