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361834-002
Technical Reference Guide
System Support
8259 Mode
The 8259 mode handles interrupts IRQ0-IRQ15 in the legacy (AT-system) method using
8259-equivalent logic. Table 4-7 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 4-7.
Maskable Interrupt Priorities and Assignments
Priority Signal
Label
Source
(Typical)
1
IRQ0
Interval timer 1, counter 0
2
IRQ1
Keyboard
3
IRQ8-
Real-time clock
4
IRQ9
Unused
5
IRQ10
PCI devices/slots
6
IRQ11
Audio codec
7
IRQ12
Mouse
8
IRQ13
Coprocessor (math)
9
IRQ14
Primary IDE controller
10
IRQ15
Sec. IDE I/F controller (not available on SATA units)
11
IRQ3
Serial port (COM2)
12
IRQ4
Serial port (COM1)
13
IRQ5
Network interface controller
14
IRQ6
Diskette drive controller
15
IRQ7
Parallel port (LPT1)
--
IRQ2
NOT AVAILABLE (Cascade from interrupt controller 2)
Summary of Contents for Compaq dc71 Series
Page 50: ...2 34 361834 002 Technical Reference Guide System Overview ...
Page 58: ...3 8 361834 002 Technical Reference Guide Processor Memory Subsystem ...
Page 126: ...5 40 361834 002 Technical Reference Guide Input Output Interfaces ...
Page 168: ...8 20 361834 002 Technical Reference Guide BIOS ROM ...
Page 188: ...A 20 361834 002 Technical Reference Guide Error Messages and Codes ...
Page 192: ...B 4 361834 002 Technical Reference Guide ASCII Character Set ...
Page 210: ...C 18 361834 002 Technical Reference Guide Keyboard ...