Sun Microsystems Enterprise 250, Owner'S Manual

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Figure 5–4
About Peripheral Component
Interconnect (PCI) Buses
All system communication with storage peripherals and network interface devices is
mediated by a UPA-to-PCI bridge, located on the system’s main logic board. This
bridge chip manages communication between the UPA bus and the system’s two PCI
buses. These PCI buses support slots for up to four PCI interface cards. One PCI bus
(bus 0) also handles communication between the system and devices connected to
the main logic board’s SCSI, FastEthernet, serial, parallel, and keyboard/mouse ports.
PCI cards come in a variety of configurations. Not all cards will fit or operate in all
PCI slots, so it is important to know the specifications of your PCI cards and the
types of cards supported by each PCI slot in the system.
Some PCI cards are as short as 6.875 inches (17.46 cm) in length (called “short”
cards), while the maximum length of PCI cards is 12.28 inches (31.19 cm, called
“long” cards). Each slot in the system can accommodate either a long or a short card.
Older PCI cards communicate over 32-bit PCI buses, while many newer cards
communicate over wider 64-bit buses. All four PCI slots will accept either 32-bit or
64-bit wide cards.
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Sun Enterprise 250 Server Owner’s Guide
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Revision A, June 1998