Subject: IISI nubus adapter in an SE/30

Pin C2 on the IIsi 68030 PDS /NuBus NuBus space address
Pin C2 on the SE/30 68030 PDS /NuBus

indicates address in the range $6000 0000 to $FFFF FFFF. This signal is active when the CPU addresses the built-in video display. (Expansion cards can use this signal and further decode the slot ranges to avoid conflict with the video logic)

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Ok, call me crazy (it wouldn't be the first time) but ... is there any value in the following approach, even for diagnostic investigations:

Make a male-female PDS-PDS riser and bring C2 from both the logic board and card side out to a jumper pair, then:

• Investigate running the adapter without C2 bridged.
  
• Connect card-side C2 to ??? on the logic board.
  
• Build [magic] that intervenes between logic-board-side and card-side C2.