Owner`s manual

be assigned or “steered” to one of the 11 available PC interrupts by either the

BIOS or Windows 98/Me. As far as the user is concerned, PCI interrupts use the

same numbers and are assigned the same way as Plug-and-Play ISA interrupts.

Note, however, that a PCI card can share an interrupt with another PCI card but

not with an ISA card.

Plug-and-Play and Interrupts

When your computer first starts up, the BIOS will check each connector slot to see

if a Plug-and-Play card is installed. Each Plug-and-Play card has built into it a list

of what resources it requires including how many interrupts it needs and which

ones it can use. The BIOS will then configure each card and, if needed, assign an

appropriate interrupt. It does this for both ISA and PCI Plug-and-Play cards.

Windows 98/Me will also check for and configure Plug-and-Play cards, possibly

changing some of the settings to suit its needs.

Legacy Cards and Interrupt Conflicts

Problems can arise when the system contains older “legacy” ISA cards with their

jumper-configured (or possibly hard-wired) interrupts. The computer’s BIOS and

Windows 98/Me have no automatic way to detect these cards and determine which

interrupts, if any, are being used. For example, you may have a MIDI card

installed with its jumpers configured to use IRQ 9. Since the BIOS cannot detect

the legacy card it will consider IRQ 9 to be a free interrupt. Consequently, it may

assign IRQ 9 to your Echo card. The next time you try and use your MIDI card or

play back audio via your Echo card, neither device will function properly.

Or, maybe you have a SCSI card that had previously been assigned to IRQ 10. The

BIOS may now decide to assign IRQ 10 to your Echo card, and move the SCSI

card to IRQ 9. An interrupt conflict now exists between the SCSI card and the

older MIDI card.

PCI Cards and Interrupt Conflicts

Some plug & play PCI cards can also cause interrupt conflicts when they try to

share an IRQ with another PCI card. Many PCI cards can share an IRQ with no

problems at all, but some just don’t like to share. For example, you may have a

network card installed, and Windows has it configured to use IRQ 10. Since that is

the only card assigned to IRQ 10, Windows assumes that it is OK to let it share

with the next PCI card that comes along. Consequently, it may assign your Echo

card to share IRQ 10. This network card happens to be unfriendly and doesn’t like

to share, so the next time you try to use it or your Echo card, neither device will

function properly.