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Programming Considerations
VMEchip2 Interrupts
2
Z8536 and Z85230 Interrupts
2-22
VMEchip2 interrupts consist of interrupts from the VMEbus IRQ lines and
from the VMEchip2 internal resources (i.e., DMA and Timers). You can
program the VMEchip2 interrupt control registers as though the system
were MC68040-based (i.e., with interrupt priority levels from 1 through 7).
When an interrupt is pending, the VMEchip2 asserts three encoded
interrupt request lines (IPL2
is then issued by the VME2PCI device to the processor through the IBC.
After learning from the IBC that the source of the interrupt is the
VME2PCI, the software determines the interrupt level to acknowledge the
VMEchip2 by examining the ILVL status bits of the Interrupt Control and
Status Register in the VME2PCI ASIC. Finally, to get the interrupt vector
from the VMEchip2, the interrupt handling routine must read the
appropriate Pseudo IACK Registers.
After learning from the IBC that the source of the interrupt is the
Z85230/Z8536 devices, the software can either poll the two devices or
perform an 8-bit read access to the Z85230/Z8536 Pseudo IACK Register
to get the interrupt vector. Refer to the Z85230 and the Z8536 Data Sheets
for programming information and additional information about their
interrupt structures.
ABT (Abort) Interrupt
The MVME1603/MVME1604 can be programmed to generate an
interrupt to the processor via ISA Interrupt IRQ8
is activated (refer also to the ABORT Switch section at the beginning of this
chapter). The ABORT
device. Refer to the 82C378ZB and the Z8536 Data Sheets for
programming information.
∗
∗
-IPL0
) to the VME2PCI device. An interrupt
∗
signal is also routed to pin PB7 of the Z8536
∗
when the
switch
ABORT
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