An amount of interruptions accessible for assignment depends on devices connected to a system. For example, if the support of a mouse is disabled in BIOS (the parameter “Mouse support”) an interruption IRQ12 will be accessible.
To assign interruptions, you may also use the parameter “Slot n IRQ”, where n – a number of PCI-slot. This parameter enables to assign a particular interruption to a slot. The numbers of the appropriate hardware interruptions are used as the values of this parameter: IRQ3, IRQ4, IRQ5, IRQ7, IRQ9, IRQ10, IRQ11. Besides, you can use the value “Auto” that enables to set an interruption number automatically. It should be stated that this parameter cannot be used in Windows 2000/XP.
Another parameter for assignment of interruptions is “PIRQ_n Use IRQ”, where n – ranges from 0 to 3. This parameter also enables to assign interruptions individually to each device on PCI and ISA-buses. In contrast to the parameter “Slot n IRQ”, this parameter has a wide range of functional possibilities. Its values indicate free or accessible IRQ-numbers. There is also the value “Auto” that enables to perform autoconfiguration of devices.
The last parameter for assignment of interruptions is “PCI Device Search Order” that enables to change the sequence of PCI-slots. This parameter may have two values: First-Last – from the first to the last (a standard bypass); Last-First – from the last to the first (a reverse bypass).