Integrated Pci Bridge - EPOX P55-TH User Manual

2-8 P55-TH

2-5 Integrated PCI Bridge

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The P55-TH utilizes Intel's 82430HX PCIset chipset to support Intel Pentium
P54C/P54CTB Processor PCI/ISA system. The Intel 82430HX PCIset chipset
consists of the 82439HX (324 Pin BGA Packing Chipset) system controller
(TXC), and one 82371SB PCI ISA/IDE Accelerator (PIIX3) bridge chip. It pro-
vides 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-TH 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 configures jumpers or worry 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.
If however, a "Legacy card" (such as plug paddle card and cable into the ISA slot.)
is plugged in the system, modification in the ROM SETUP UTILITY become
necessary. First, enter PNP/PCI CONFIGURATION SETUP utility from ROM
SETUP UTILITY main menu to set the "IRQ X or DMA X assigned to: legacy
ISA or PCI/ISA PNP"cards.
Second, you must be enter CHIPSET FEATURES SETUP UTILITY from ROM
SETUP UTILITY main menu and set the " Onboard Primary PCI IDE: Disabled
and Onboard Secondary PCI IDE: Disabled." When you plugged the PCI/ISA
IDE card into the system. You will Disabled Onboard Primary and Secondary
PCI IDE from CHIPSET FEATURES SETUP UTILITY too.
Some "Legacy card" ( no paddle card and cable.) you can set the system interrupt
request (IRQ) on the "Legacy card" (refer to user's manual of the card) to a proper
system IRQ level (in general, card's Primary assigned to INTA and Secondary
assigned to INTB). If the card is plugged into slot 1(marked PCI#1), you can not
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 enter PNP/PCI
CONFIGURATION SETUP utility from ROM SETUP UTILITY main menu
and set the "IRQ X or DMA X assigned to : Legacy ISA or PCI/ISA
PNP"(depend on which IRQ X or DMA X was used to Legacy card that is plugged
into ISA or PCI slot.
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