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MOTOROLA
13
3.3 ILEGACY
The ILEGACY switch is used to select between standard SP3 interrupt connections and support for legacy
interrupt connections.
3.3.1 IMODE
The IMODE switches are connected to the SPF FPGA to configure the PCI interrupt connections.
3.3.1.1 IMODE Serial
When IMODE is set such that Serial is selected, the SPF100 enables an internal serial multiplexer that works
with the serial demultiplexer in the EPIC portion of the MPC107 or MPC824X on MPMC cards. This allows
many interrupts to be conveyed to the MPMC than would normally be possible with the four allocated pins.
shows the serial ‘slot’ corresponding to each external interrupt
Table 11. Sandpoint 3 ILEGACY Switches
ILEGACY
Definition
Notes
SW2-3
On (right)
Standard SP3 Interrupt Modes
Default
Off (left)
Legacy Sandpoint 1/2 Interrupt Modes
See Appendix B
Table 12. Sandpoint 3 IMode Switches
IMODE[0:1]
Definition
Notes
SW2-4
SW2-5
On (right)
On (right)
Serial
Default.
On (right)
Off (left)
Wire-OR
Off (left)
On (right)
Slot
Not available on all systems.
Off (left)
Off (left)
reserved
Table 13. Sandpoint 3 Serial Interrupt Slot Assignment
Slot
Interrupt Source
Note
0
SIOINT
Inverted, so active low
1
reserved
reserved
2
SLOT #1
INTA# from each slot.
3
SLOT #2
4
SLOT #3
5
SLOT #4
6
WinBond INTA#
No specific function