Assigning Irqs For Expansion Cards - Unicorn Electronics ENDAT-3201M User Manual

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User's Manual
Please using the default setting as above if you are not familiar with the configuration of raiser card
and add-on card.
Caution: Do not insert PCI Bus Add-On cards directly into the on-board expansion slot!

2-5. Assigning IRQs for Expansion Cards

Some expansion cards require an IRQ (Interrupt request vector) to operate. Generally, each
IRQ must be exclusively assigned to specific use. In a standard design, there are 16 IRQ
available with 11 of them already in used by other part of the system.
Both ISA and PCI expansion cards may need to use IRQ. Cards installed in the ISA
Expansion Bus have the first priority to use the available system IRQs. Any remaining IRQ
then, may be assigned to this PCI Bus. Microsoft's Diagnostic (MSD.EXE) utility included
in the Windows directory can be used to see their map. Make sure that there are no two
devices using the same IRQ in the system. Otherwise this will cause the system to hang up or
give unexpected results. To simplify the process, this motherboard complies with the Plug
and Play (PnP) specifications, which was developed to allow automatic system configuration.
Whenever a PnP-compliant card is added to the system, PnP cards and IRQs are
automatically assigned if 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 configuration in the BIOS setup utility can be used to indicate which IRQs have 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 is automatically assigned an IRQ to a
PCI slot that has a card in it which requires an IRQ. To install a PCI card, you need to set the
correct "ADSEL" and "INT" (interrupt) assignment. Please refer to "Chapter 2-5" Installing
a Riser Card for detail assignments.