On the a1200 you can only use a blizzard vision with the blizzardppc but if you have a mediator or another one you can use pc gfx boards, if a game or application only use amiga custom chips this signal output its only on the 1200 native rgb (or composite video) on the a4000 some gfx boards like cybevision comes with a scandoubler appart and show all the signals throught gfx board vga output.
Hope you understad my crap explanations.
