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32 ASUS K7M User’s Manual
3. HARDWARE SETUP
Expansion Cards
3. H/W SETUP
Some expansion cards need to use an IRQ to operate. Generally, an IRQ must be
exclusively assigned to one use. In a standard design, there are 16 IRQs available
but most of them are already in use, leaving 6 IRQs free for expansion cards. If your
motherboard has PCI audio onboard, an extra IRQ will be used, leaving 5 IRQs
free. If your motherboard has ISA audio onboard, an extra 3 IRQs will be used,
leaving 3 IRQs free.
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 expan-
sion card design, now referred to as legacy ISA cards, requires that you configure
the card’s jumpers manually and then install it in an 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. 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 assigned
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 assigns an
IRQ to PCI cards that require an IRQ. To install a PCI card, you need to set an 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.
3.7.3 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 4.4.4 Plug and Play Setup for those IRQs and DMAs you want to
reserve).