Making a 3D Graphics Card for the Atari 800 XL using the Raspberry Pi

[Mark loves Stella]

Element 14 did a pretty cool project making a 3D graphics card using a Raspberry Pi attached through the Atari expansion port. 

 

[Rybags]

Nice that they're doing this but as it stands the Atari is just being used as a glorified input device, merely processing driving controller input into delta values to pass to the Pi.

He mentioned it being slow and better done in assembly which is fairly obvious - though from what you can see of the Basic program there's plenty of room for improvement.

But mouse/driving input processing is best done by sampling multiple times per frame in a reasonably jitter free manner so obviously asm would do much better.

 

What would be better overall IMO is say, if it snooped the buses and did some Antic emulation at the Pi side and allowed blending the graphics from the two (though to do so you'd probably want to tap the /Halt line which would have to be done internally.

[Wrathchild]

Indeed, this is UNO Cart territory (though again the A8 there can be seem as a glorified input device) but as @Rybags suggests, the display data is fed to Antic.

 

 

 

[Rybags]

Maybe that approach would be the way to go - have the Pi able to generate graphics that the Atari can display simply by responding to memory accesses in a particular window that you set (sort of like how VBXE can do it)

 

But, it potentially becomes another enhancement in an already crowded and under-supported market.  And likely would cost as much as a VBXE also (I have a bare Pi 3B+ which including case came to a bit over $100 here)