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3.4.1
ARMING AND DISARMING MASKABLE INTERRUPTS
North Star HSIO-4
To arm maskable interrupts for a port, set
the particular bit(s) in the mask that
corresponds to the interrupt —
combination of interrupts —
use. This is done by outputting the value
for the required bit pattern to the
Interrupt Mask Set I/O address for the
relevant port.
As shown in Table 3-9, there are a total of
eight possible bit patterns. When output to
the Interrupt Mask Set address for a
particular port, the bit pattern establishes
the status (arm/disarm) of all three maskable
interrupts for that port. Table 3-9 shows the
values that correspond to each of the eight
possible bit patterns. Table 3-1 shows the
Interrupt Mask Set addresses for each port.
For example: Assuming that the HSIO-4 board is
addressed starting at 10H, to arm the Tx Ready
interrupt (and disarm the other two
interrupts) for Port C, you would output 02H
to I/O address 19H (the Interrupt Mask Set
I/O Address for Port C).
Similarly, to disarm all three maskable
interrupts for port C, you would output 00H to
I/O address 19H.
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