Interrupts
This system :supports the full range of 68000 processor interrupts.
The
various kinds of
interrupts generated by the hardware are brought into the peripherals chip and are
translated into six of the seven available interrupts of the 68000.
NO
NMAS
KABLE
INTERRUPT
Interrupt level 7 is the nonmaskable interrupt and
is
not generated anywhere
in
the
current system.
The
raw interrupt lines of the 68000, IPL2 through
IPLO,
are brought
out
to the expansion connector and can be used
to
generate this level 7 interrupt for
. debugging purposes.
MAS
KABLE
INTERRUPTS
Interrupt levels 1 through 6 are generated. Control registers within the peripherals chip
allow you
to
mask certain of these sources and prevent them from generating a 68000
interrupt.
USER
INTERFACE
TO
THE
INTERRUPT
SYSTEM
The
system software has been designed
to
correctly handle all system hardware inter-
rupts
at
levels 1 through
6.
A separate set of input lines, designated INT2* and INT6* 1
have been routed to the expansion connector for use by external hardware for interrupts.
These are known as the external
low-
and external high-level interrupts.
These interrupt lines are connected
to
the peripherals chip and create interrupt levels 2
and
6,
respectively.
It
is recommended
that
you take advantage of the interrupt
handlers built into the operating system by using these external interrupt lines rather
than
generating interrupts directly on the processor interrupt lines.
1 A * indicates
an
active
low
signal.
System Control Hardware
207
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