Echo Audio MiaMIDI Owner's Manual download pdf (Page 84)

configuring jumpers on the card. Newer Plug-and-Play ISA cards have their

interrupts selected by either the computer’s BIOS (the built-in program that starts

the computer) or by Windows 98/Me.

The newer PCI (Peripheral Connect Interface) bus transfers data faster than ISA

and was designed to support Plug-and-Play from the start. PCI connectors have

only four interrupts wired to them (A, B, C, and D). However, these interrupts can

be shared by more than one PCI connector slot and each connector’s interrupt can

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

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Echo Audio MiaMIDI Owner's Manual Page 84