The Indivision is connected internally.
The 2nd source (gfx-card) can be connected internally (cvppc/bvppc) or externally (every other gfx-card).
The org.design from chkamiga works with a patch for cgfx-systems and switching over a par.port-line.
With hgfx I wrote some kind of snoopcode for the viewport many years ago (resync-tool).
I decided to use this codebase for a compatible way of monitorcontrolling (no cgfx or p96 patching).
Snooping the Viewport for known AGA-modes forced the switch to AGA-Indy Input ... all other modes are switched to the 2nd source (gfx-card).
For controlling I think it is better to use a line from the serial port, because nowadays most people are using par.port printers and lan for dsl.
Ser.+modem seems to be dead , but I try to use one line from cts or rts, so it could be possible to use the ser.port without rts/cts handshake settings.
< more pictures >
with these kind of switch it is possible to use a indy+radeon pci -combo with the same comfort like an compserv aga flifi + cv64 combo.
only a little bit more uptodate.