D-Box 1200 Questions

[doctorq]

what i wanted to know was do you need the AT-ATX converter?

Not if you get one of the newer ones like SX or TX. You only need the converter if the Mediator board is one of the old ones with a P8 and P9 connector (like the LT4 and earlier boards).

Also if you get a TV card with the mediator can you route the amiga native video into that and then display it on your screen? sort of like a way of getting around not having a scan doubler.

For WHDLoad games, yes, but for early boot menu and disk loaded games, no.

[doctorq]

When playing WHDLoad games the RTG screen goes black and the native AGA screen that was Grey/White plays the game...
Well... running the Mediator TVTuner Program with the Composite Input theoretically might work ONLY in full screen IF it overlays the black RTG screen.
I haven't tried it despite I have an TVTuner in my Mediator TX  so I don't know if it can be done but you can try it.
Apart from that, I have the impression that the quality would kind suck imho.

It can be done. It's just a matter of changing the DISPLAYCHAIN setting in the Voodoo monitor driver to the opposite of what it is now.

The quality is OK, but could be better.