Integrated Pci Bridge - EPOX P55-TX 2 User Manual

2-10 P55-TX 2

2-6 Integrated PCI Bridge

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The P55-TX 2 utilizes Intel 430TX PCIset chipset to support Intel Pentium Proces-
sor PCI/ISA system. The Intel 82430TX PCIset chipset consists of one 82439TX
system controller (MTXC) and one 82371AB PCI ISA/IDE Accelerator (PIIX4) bridge
chip. It provides an interface which translates CPU cycle into PCI bus cycle and PCI
burst read/write capability. In addition, it provides a high performance PCI arbiter and
supports four PCI Masters, Rotating Priority Mechanism, and Hidden Arbitration
Scheme Minimizes Arbitration Overhead. The 82371AB(PIIX4) supports PCI Specifi-
cation Revision 2.1 Compliant and contains a Universal Serial Bus interface with both
host and hub control functions. P55-TX 2 reserves a USB connector to provide two
USB ports for serial transfer at 12 or 1.5 Mbit/sec. This supports legacy keyboard
and mouse software with USB-Base Keyboard and mouse.
There are four interrupts in each PCI slot : INTA#, INTB#, INTC#, and INTD#, since
the P55-TX 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 interrupts
used by ISA add-in cards in the BIOS Setup utility.
If a "Legacy card" (such as plug paddle card and cable for the ISA slot.) is plugged
in the system, modification in the ROM SETUP UTILITY becomes necessary. First,
enter PCI CONFIGURATION SETUP utility from ROM SETUP UTILITY main menu
to set the "PCI IDE IRQ MAP TO : ISA".
Second, you must enter CHIPSET FEATURES SETUP UTILITY from ROM SETUP
UTILITY main menu and set the " Onboard Primary PCI IDE: Disabled and Onboard
Secondary PCI IDE: Disable." When you plug the PCI/ISA IDE card into the system,
You should Disable Onboard Primary and Secondary PCI IDE from CHIPSET
FEATURES SETUP UTILITY too.
When no paddle card and cable are used, 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 is assigned to INTA and Secondary is assigned
to INTB). If the card is plugged into slot 1(marked PCI#1), you cannot use the
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 PCI CONFIGURA-
TION SETUP utility from ROM SETUP UTILITY main menu and sets the " PCI IDE
IRQ MAP TO : PCI-Slot 1" (It depends on the slot # where the Legacy card is
plugged).