82C836 Datasheet, PDF (77/205 Pages) List of Unclassifed Manufacturers – Single-Chip 386sx AT

Section 7
Interrupt Controller
The 82C836 incorporates two programmable interrupt controllers compatible with the
Intel 8259A. The controllers accept requests from peripherals, resolve priority on
pending interrupts and interrupts in service, issue an interrupt request to the CPU, and
provide a vector used as an index by the CPU to determine which interrupt service
routine to execute. A variety of priority assignment modes are provided, which can be
reconfigured at any time during system operation; allowing the complete interrupt
subsystem to be restructured, based on the system requirements. The controllers are
cascaded in a fashion compatible with the IBM PC/AT. Table 7-1 shows the interrupt
levels used by the system board and I/O channel. The interrupts are shown by priority,
starting with the highest level.
Table 7-1. Interrupt Levels for System Board
Interrupt
NMI
IRQ0
IRQ1
IRQ8*
IRQ9
IRQ10
IRQ11
IRQ12
IRQ13
IRQ14
IRQ15
IRQ3
IRQ4
IRQ5
IRQ6
IRQ7
System Board
Parity check
Timer
Keyboard
Real Time Clock
Not used
Not used
Not used
Not used
Coprocessor
Not used
Not used
Serial port 2
Serial port 1
Parallel port 2
Hard Disk and Floppy Disk
Parellel port 1
* In internal RTC mode, IRQ8 is an internal signal.
I/O Channel
IOCHCK
Not available
Not available
Not avaiable
Available
Available
Available
Available
Not available
Available
Available
Available
Available
Available
Available
Available
Chips and Technologies, Inc.
PRELIMINARY
Revision 3.0 7-1