Integrated Pci Bridge - EPOX P55-VP 2 User Manual

Hardware Design 2-7

2-5 Integrated PCI Bridge

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The P55-VP 2 utilizes PCIset chipset to support Intel Pentium Processor PCI/ISA
system. The VIA Apollo VPX PCIset chipset consists of the 82C585VP system
controller (TSC), two 82C587VP Data Path (TDP) devices, and one 82C586A PCI ISA/
IDE Accelerator bridge chip. It provides an interface which translates CPU cycle into
PCI bus cycle, and PCI burst read/write capability. In addition, it provides high
performance PCI arbitor to support four PCI Masters, Rotating Priority Mechanism,
and Hidden Arbitration Scheme Minimizes Arbitration Overhead.
There are four interrupts in each PCI slot : INTA#, INTB#, INTC#, and INTD#. Since
the P55-VP 2 adapts the PCI auto-configuration with the system BIOS Setup utility.
When the system is turned on after adding a PCI add-in card, the BIOS automatically
configure interrupts, DMA channels, I/O space, and other paramaters. You do not
have to configure jumpers or worry about potential resource conflicts. Because PCI
cards use the same interrupt resource as ISA cards, you must specify the interrupt
used by ISA add-in cards in the BIOS Setup utility.
However, if a "Legacy card" (such as plugging a paddle card and cable into an ISA
slot) is plugged in the system, modification in the ROM SETUP UTILITY becomes
necessary. First of all, you must enter PCI CONFIGURATION SETUP utility from
the ROM SETUP UTILITY main menu to set "ISA" for the "PCI IDE IRQ MAP TO
Secondly, you must enter the CHIPSET FEATURES SETUP UTILITY from the ROM
SETUP UTILITY main menu and set "Disable" for the " Onboard Primary PCI IDE
and the Onboard Secondary PCI IDE. When you plug PCI/ISA IDE cards into the
system, You should select "Disabled" for the Onboard Primary and Secondary PCI
IDE from the CHIPSET FEATURES SETUP UTILITY too.
You can set the system interrupt request (IRQ) on some "Legacy cards" which have
on paddle card and cable. (refer to user's manual of the card) to a proper system IRQ
level (In general, card's Primary is assigned to INTA and Secondary is assigned to
INTB). If the card is plugged into slot 1(marked PCI#1), you cannot use second slot
(marked PCI#2) because the Secondary INT signal takes INTB from the slot (refer to
Page 3-12 for circuit diagram). The user then enters the PCI CONFIGURATION
SETUP utility from the ROM SETUP UTILITY main menu and set "PCI-Slot 1" for
the "PCI IDE IRQ MAP TO (This depends on the slot # where the Legacy card is
plugged).
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