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3.3 Interrupt Functions
3.3.1 Introduction
Two lines of each I/O port C, plus ports A0 and B0, are connected to the
interrupt circuitry. The "Interrupt Control Register" of the PCM-3753I
controls how the combination of these signals generates an
interrupt. Six interrupt request signals can be generated at the same time,
and then the software can service these six request signals by IRQ. The
multiple interrupt sources provide the card with more capability and
flexibility.
3.3.2 IRQ Level
The IRQ level is set automatically by the PCI plug-and-play BIOS and is
saved in the PCI controller. There is no need for users to set the IRQ
level. Only one IRQ level is used by this card, although it has six
interrupt sources.
3.3.3 Interrupt Control Registers
The "Interrupt Control Registers" (Base + 16, 17, 18 and 19 for the
PCM-3753I, and Base + 48, 49, 50 and 51 for the PCM-3753IE) control
the interrupt signal sources, edges and flags. The following table shows
the bit map of each interrupt control register. These registers are read-
able/writable. When writing to one of them, it is used as a control regis-
ter, and when reading from it, it is used as a status register.
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Chapter 3
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