Specifications

System BIOS and Resources
System Resources
Chapter 464
Three major interrupt modes are available:
• PIC mode: This mode uses only legacy interrupt controllers, so the
system can support only one processor. You can select this mode when
you install Windows NT.
• Virtual wire mode: This mode, which is implemented using the
82C59 interrupt and the I/O APIC controller, is used during boot
time. The virtual wire mode allows the transition to the symmetric
I/O mode. In the virtual wire mode, only one processor executes
operations.
• Symmetric I/O mode: This mode is implemented using the I/O
APIC controller and allows for multiple processor operations.
NOTE In PIC mode and virtual wire mode, PCI interrupts are routed to the INT
line. In symmetric I/O mode, PCI interrupts are routed to the I/O APIC
controllers and forwarded over an APIC bus to the processors.
INTIN15 IRQ15 ICH - Integrated IDE Controller
(secondary)
INTIN16 PCINTA
INTIN17 PCINTB
INTIN18 PCINTC
INTIN19 PCINTD
INTIN20 TFPC IRQ
INTIN21 SCI IRQ
INTIN22 not
connected
INTIN23 ICH SMI
(not used)
I/O APIC Input IRQ IRQ Description