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7
7-7
Programming Device PG 740
C79000-G7076-C742-01
7.2
Interrupt Assignments
The PG 740 uses two integral interrupt controllers of type 82C59 to handle
the 16 hardware interrupts (IRQ 0 to IRQ 15).
The INT output of the slave controller is connected to the IRQ 2 input of the
master controller. Interrupt 9 (IRQ 9) can be used on the bus for the assigned
interrupt 2 (IRQ 2). In the initialization phase, IRQ is programmed for the
software interrupt vector 0A H (IRQ 2) by the ROM-BIOS.
The interrupts are priority-scheduled in the reverse order of their numbering.
Interrupt IRQ 0 has the highest priority and interrupt IRQ 7 the lowest. For
triggering IRQ 2, interrupt IRQ 8 has the highest priority and interrupt IRQ15
the lowest. Interrupts IRQ 8 to IRQ 15 therefore have priority over interrupts
IRQ 3 to IRQ 7. The interrupt vectors are initialized and masked when the
PG 740 is powered up.
Table 7-5
I/O Addresses of the Interrupt Controllers
List of Hardware Interrupts
Programmed
Interrupt
Vector; Memory
Address
SMI
System management interrupt; cannot be masked
-
NMI
I/O channel parity
INT 2 H
IRQ 0
Timer output 0; I/O controller (ISP), internal
INT 8 H
IRQ 1
Keyboard (output buffer full)
INT 9 H
IRQ 2
Interrupt from slave interrupt controller
INT A H
IRQ 3*)
Serial port (COM2)
INT B H
IRQ 4*)
V.24/V.28 interface; serial port (COM1/TTY)
INT C H
IRQ 5*)
Parallel port 2 (LPT2) / MPI
INT D H
IRQ 6*)
Diskette
INT E H
IRQ 7*)
Parallel port, printer 1 (LPT1)
INT F H
IRQ 8*)
Real-time clock (RTC), low active
INT 70 H
IRQ 9*)
Software interrupt rerouted to 0AH (IRQ 2) (VGA)
INT 71 H
IRQ 10*)
ETHERNET (CP1413)*)
INT 72 H
IRQ 11*)
INT 73 H
IRQ 12*)
Trackball or PS/2 mouse
INT 74 H
IRQ 13
Numeric processor
INT 75 H
IRQ 14*)
IDE interface primary
INT 76 H
IRQ 15*)
IDE interface secondary
INT 77 H
*) These signals are fed to the two I/O connectors and can also be used by the
PCMCIA interface.
Do not use interrupts already assigned in the system.
Interrupt
Assignment
Priority
I/O Addresses of
the Interrupt
Controllers
Hardware Information