28 ASUS CUBX User’s Manual
Both ISA and PCI expansion cards may require IRQs. System IRQs are available to
cards installed in the ISA expansion bus first, then any remaining IRQs are available
to PCI cards. Currently, there are two types of ISA cards.
The original ISA expansion card design, now referred to as legacy ISA cards, re-
quires that you configure the card’s jumpers manually and then install it in any
available slot on the ISA bus. To see a map of your used and free IRQs in Windows
98, the Control Panel icon in My Computer, contains a System icon, which gives
you a Device Manager tab. Double-clicking on a specific hardware device gives
you the Resources tab which shows the Interrupt number and address. Double-click
Computer to see all the interrupts and addresses for your system. Make sure that no
two devices use the same IRQ or your computer will experience problems when
those two devices are in use at the same time.
To simplify this process, this motherboard complies with the Plug and Play (PNP)
specification which was developed to allow automatic system configuration when-
ever a PNP-compliant card is added to the system. For PNP cards, IRQs are as-
signed automatically from those available.
If the system has both legacy and PNP ISA cards installed, IRQs are
assigned to PNP cards from those not used by legacy cards. The PCI and PNP con-
figuration of the BIOS setup utility can be used to indicate which IRQs are being
used by legacy cards. For older legacy cards that do not work with the BIOS, you
can contact your vendor for an ISA Configuration Utility.
An IRQ number is automatically assigned to PCI expansion cards after those used
by legacy and PNP ISA cards. In the PCI bus design, the BIOS automatically as-
signs an IRQ to PCI cards that require an IRQ. To install a PCI card, you need to set
the INT (interrupt) assignment. Since all the PCI slots on this motherboard use an
INTA #, be sure that the jumpers on your PCI cards are set to INT A.
Assigning DMA Channels for ISA Cards
Some ISA cards, both legacy and PNP, may also need to use a DMA (Direct Memory
Access) channel. DMA assignments for this motherboard are handled the same way
as the IRQ assignment process described earlier. You can select a DMA channel in
the PCI and PNP configuration section of the BIOS Setup utility.
IMPORTANT: To avoid conflicts, reserve the necessary IRQs and DMAs for
legacy ISA cards (see 4.4.3 PCI Configuration. Choose Yes in IRQ xx Used By
ISA and DMA x Used By ISA for those IRQs and DMAs you want to reserve).
DMA Channels
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