There's this thing also:
http://www.bigbookofamigahardware.com/bboah/product.aspx?id=351It would be nice to be able to plug an inexpensive single board computer into the passive backplane on the amiga motherboard. Then have a "dumb" bridge board that gave the single board computer access to amiga memory and devices (and the other way around).
Even if we skipped the custom bridge board thingy and connected the computers externally over some high speed serial ports or ethernet, this might be an interesting upgrade.
brian
