Integrated Pci Bridge - EPOX P55-BT User Manual

2-10 P55-BT

2-6 Integrated PCI Bridge

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The P55-BT utilizes Intel 430TX PCIset chipset to support Intel Pentium Processor
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-BT 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-BT 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 Disabled Onboard Primary and Secondary PCI IDE from CHIPSET
FEATURES SETUP UTILITY too.
When 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 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 CONFIGURATION 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).