C.1.2 Pci Bus - Sun Microsystems Enterprise 220R Service Manual

C.1.2 PCI Bus
The peripheral component interconnect (PCI) bus is a high-performance 32-bit or
64-bit bus with multiplexed address and data lines. The PCI bus provides electrical
interconnection between highly integrated peripheral controller components,
peripheral add-on devices, and the processor/memory system.
There are two PCI buses. The first bus is a one-slot, 3.3-VDC, 64-bit or 32-bit,
66-MHz or 33-MHz bus. The second bus is a three-slot, 5.0-VDC, 64-bit or 32-bit,
33-MHz bus. Each bus is controlled by the UPA-to-PCI bridge (U2P) ASIC. There are
also two on-board controllers, the Symbios 53C876 SCSI controller and the
PCI-to-Ebus/Ethernet controller (PCIO) ASIC, on the 33-MHz PCI bus.
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Functional Description