Abit AT7-MAX2 User Manual page 56

Introducing the BIOS
request (IRQ) line assigned to the VGA on your system. Activity of the selected IRQ always awakens the
system.
You can assign an IRQ for the either PCI or AGP VGA or Disabled.
Allocate IRQ to USB:
Two options are available: Disabled or Enabled. The default setting is Enabled. If you need free up
another IRQ, you can choose to disable this item to an IRQ. However, some situations in Windows
may cause the USB port to malfunction or experience other problems!
PCI Latency Timer(CLK):
The options are: 32, 64, 96, 128, 160, 192, 224, and 248. The default setting is 32. This option selects the
controls for the amount of time that the VIA 8235 arbiter allows a PCI initiator to perform multiple
back-to-back transactions on the PCI bus.
PIRQ_0 Use IRQ No. ~ PIRQ_3 Use IRQ No.:
Eleven options are available: Auto, 3, 4, 5, 7, 9, 10, 11, 12, 14, 15. Default setting is Auto. This item
allows the system to automatically specify the IRQ number for the device installed on PCI slots. This
means that the system can specify the fixed IRQ number for the device installed on the PCI slots (or
onboard PCI devices). This is a useful function for when you want to fix the IRQ for a specific device.
For example, if you want to move your hard disk to another computer and don't want to re-install
®
Windows NT or Windows
computer to fit the original computer settings.
This feature is for the operating system that will record and fix the PCI configuration status if you want to
change it.
For the relations between the hardware layout of PIRQ (the signals from the VIA VT8235 chipset), INT#
(means PCI slot IRQ signals) and devices, please refer to the table below:
SIGNALS PCI
Slot 1
PIRQ_0 INT D
Assignment
PIRQ_1 INT A
Assignment
PIRQ_2 INT B
Assignment
PIRQ_3 INT C
Assignment
PCI slot 2 shares IRQ signals with HPT 374.
PCI slot 1 and 5 share an IRQ.
PCI slot 3 and USB 2.0 controllers share an IRQ.
PCI slot 4, IEEE1394 controllers and the AGP slot share an IRQ.
If you want to install two PCI cards into those PCI slots that share IRQ with one another at the
same time, you must make sure that your OS and PCI devices' driver supports the IRQ sharing
function.
®
2000, you can simply specify the IRQ for the device installed on the new
PCI PCI PCI
Slot 2 Slot 3 Slot 4
INT C INT B INT A
INT D INT C INT B
INT A INT D INT C
INT B INT A INT D
PCI USB 2.0
Slot 5
INT D x
INT A INT B
INT B INT C
INT C INT A
Note
IEEE 1394 HPT 374
INT A x
x x
x INT A
x x
User's Manual
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95
AGP
INT A
INT B
x
x