On a similar note, I've always wondered if it wouldn't be able to do chunky->planar conversion. Like a graffiti compatible device.
When I first got my BlizzardPPC and before I got an RTG card, I was struck with an idea that has always left me a bit curious since. In the day, I used to use Shapeshifter and there was a PPC enabled external video driver called SavagePPC (
Demo version here), which as the name implies, used the PPC to handle C2P conversion and, in the full version, supported 15-bit modes on AGA using a HAM based C2P routine.
Now, phase5 shipped an AGA driver with CyberGraphX. It allowed applications that relied on CGX calls to work on AGA screenmodes, provided they would work with 256 colour modes. However, it wasn't really much of a display driver, but it did show that you could use the native display as a CGX back end, albeit only in 8-bit modes.
My idea, although I've never seriously made a feasibility study of it, was to design an RTG driver that used Fast RAM for chunky bitmaps in 8/16/24/32 bit depths and passing that back as the BitMap whenever a CGX compatible one is asked for. So, when opening, say, a 16-bit screen, what you'd actually get was an 8-bit screen opened and a 16-bit chunky buffer in fast ram. Using a blanking interrupt, the PPC would kick in and do any required RGB->HAM conversion and C2P on the areas of the screen that appear to have changed in a manner similar to the SavagePPC EVD. If it could be made to work, then you could also implement basic blitter routines (block move, fill, scale etc) that would also use the PPC when processing areas of the chunky buffer large enough to mask the context-switch time (and simply doing it on the 68K when the areas are too small to be worth it).
The idea pretty much died when I got a graphics card, though I still wonder about it from time to time, especially with the IndivisionAGA HighGFX stuff. The notion of a 15 bit RTG display running at 1024x768 on AGA makes me smile.
