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AR-B1474 User¡ ¦ s Guide
2.3 INTERRUPT CONTROLLER
The equivalent of two 8259 Programmable Interrupt Controllers (PIC) are included on the AR-B1474 card. They
accept requests from peripherals, resolve priorities on pending interrupts in service, issue interrupt requests to the
CPU, and provide vectors which are used as acceptance indices by the CPU to determine which interrupt service
routine to execute.
Following is the system information of interrupt levels:
In Interrupt Level
NMI
CTRL1
IRQ 0
IRQ 1
IRQ 2
IRQ 3
IRQ 4
IRQ 5
IRQ 6
IRQ 7
2-2
Description
Parity check
CTRL2
System timer interrupt from timer 8254
Keyboard output buffer full
IRQ8 : Real time clock
IRQ9 : Rerouting to INT 0Ah from hardware IRQ2
IRQ10 : Spare
IRQ11 : Spare
IRQ12 : Spare
IRQ13 : Math. coprocessor
IRQ14 : Hard disk adapter
IRQ15 : Spare (Watchdog Timer)
Serial port 2
Serial port 1
Parallel port 2
Floppy disk adapter
Parallel port 1
Figure 2-1 Interrupt Controller
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