1-10 Technical Information
Interrupt Controller
The interrupt controller operates as an interrupt manager for the entire system environment.
The controller accepts requests from peripherals, issues interrupt requests to the processor,
resolves interrupt priorities, and provides vectors for the processor to determine which
interrupt routine to execute. The interrupt controller has priority assignment modes that can
be reconfigured at any time during system operations.
The interrupt levels are described in Table Section 1-4. Interrupt-level assignments 0
through 15 are in order of decreasing priority. See Section 2, “Setup and Operation”, for
information on changing the interrupts using Setup.
Table Section 1-4 Interrupt Level Assignments
Interrupt Priority
Interrupt Device
NMI
I/O channel check
IRQ00
Reserved, Interval Timer
IRQ01
Reserved, Keyboard buffer full
IRQ02
Reserved, Cascade interrupt from slave
IRQ03
Serial Port 2
IRQ04
Serial Port 1
IRQ05
On-board audio (on multimedia configurations) or
User Available
IRQ06
Diskette Drive Controller
IRQ07
Parallel Port 1
IRQ08
Real-time clock
IRQ09
On-board audio (on multimedia
configurations) or User Available
IRQ10*
User Available (SCSI board for SCSI
configurations)
IRQ11*
Video board
IRQ12
On-board mouse port (available if no PS/2 mouse)
IRQ13
Reserved, Math Coprocessor
IRQ14
Primary IDE
IRQ15
Secondary IDE if present, or else user available
* These slots are selected and used by the installed expansion boards.
