AC450NX Rack Server System Product Guide
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32- bit PCI Expans ion Slots

Six 32-bit PCI bus master slots (two primary and four secondary) on the PHP I/O baseboard
provide expansion enhancement. One 32-bit primary slot shares a common chassis expansion slot
with the ISA slot; you can use the shared slot for either PCI or ISA but not both. The PCI bus
operates at 33 MHz and provides:
• 32-bit memory addressing
• +3.3 V and +5 V environments
• burst transfers of up to 133 MB/sec
• 8-, 16-, or 32-bit data transfers
• plug and play configuration
• hierarchical bus to maximize connectivity
✏NOTE
Add-in video boards must be installed in the 32-bit primary PCI slots.

64- bit PCI Hot-plug Expansion Slots

Four 64-bit PCI hot-plug bus master slots on the PHP I/O baseboard provide maximum
performance at the wider bus width.
✏NOTE
Both 32-bit and 64-bit PCI boards may be installed in the 64-bit slots.
However, the 32-bit boards will not take advantage of the extra bandwidth
provided by the 64-bit bus.
Add-in video boards must be installed in the 32-bit primary PCI slots.

ISA Expans ion Slot

The ISA bus master slot on the PHP I/O baseboard provides for legacy expansion. The ISA slot
shares a common chassis I/O expansion slot with a 32-bit PCI slot; you can use the shared slot for
either ISA or PCI but not both. The ISA bus operates at up to 8.33 MHz and provides
• 24-bit memory addressing
• type A transfers at 5.33 MB per second
• type B transfers at 8 MB per second
• 8- or 16-bit data transfers
• interrupt sharing