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
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