Apic Mode - HP Compaq d330 DT Technical Reference Manual

8259 Mode
The 8259 mode handles interrupts IRQ0-IRQ15 in the legacy (AT-system) method using 8259-
equivalent logic. Table 4-6 lists the standard source configuration for maskable interrupts and
their priorities in 8259 mode. If more than one interrupt is pending, the highest priority (lowest
number) is processed first.
Table 4-6. Maskable Interrupt Priorities and Assignments
Maskable Interrupt Priorities and Assignments
Priority Signal Label
1 IRQ0
2 IRQ1
3 IRQ8-
4 IRQ9
5 IRQ10
6 IRQ11
7 IRQ12
8 IRQ13
9 IRQ14
10 I RQ15
11 IRQ3
12 IRQ4
13 IRQ5
14 IRQ6
15 IRQ7
-- IRQ2

APIC Mode

The Advanced Programmable Interrupt Controller (APIC) mode provides enhanced interrupt
p rocessing with the following advantages:
♦ Eliminates the processor's interru
♦ Programmable interrupt priority
♦
Additional interrupts (total of 24)
The APIC mode accommodates eight PCI interrupt signals (INTA-..INTH-) for use by PCI
d evices. The PCI interrupts are evenly distributed to minimize latency and wired as follows:
82801 PCI
Int. Cntlr. Slot 1
INTA- IN TA-
INTB-
INTC- IN
W ired
INTD-
to
INTE-
INTF- INTC-
INTG- IN TD-
INTH-
NOTES:
[1] Connection internal to the IC
other functions using INTA.
ST, SFF, DT. MT, CMT form factors o
ST, DT, MT, CMT form factors only.
Table 4-6.
Source (Typical)
Interval timer 1, counter 0
Keyboard
Real-time clock
Unused
PCI devices/slots
Audio codec
Mouse
Coprocessor (math)
Primary IDE controller
Secondary IDE I/F controller
Serial port (COM2)
Serial port (COM1)
Network interface controller
Diskette drive controller
Parallel port (LPT1)
NOT AVAILABLE (Cascade from interrupt controller 2)
pt acknowledge cycle by using a separate (APIC) bus
PCI PCI
Slot 2 Slot 3 Slot 4
INTD- INTC- INTB-
— — —
TB- INTA- INTD- INTC-
— — —
— — —
INTB- INTA- INTD-
INTC- INTB- INTA-
— — —
H. Will be reported by BIOS as using INTA but is NOT shared with
nly.
hp compaq d330 and d530 Series of Personal Computers
Featuring the Intel Pentium 4 Processor
First Edition - June 2003
Technical Reference Guide
PCI PCI AGP
Slot 5 Slot
IN TD- —
— — —
INTA- INTA-
— — IN TB-
— — —
INTB- —
IN TC- —
— — —
NIC USB
I/F [1] I/F #2
— —
— —
— —
— —
IN TA- —
— —
— —
— INTC-
4-15