A little demo to learn how to use the stack to quickly blit to the screen.

The fastest way is to use precalculate screen locations and a buffer. I was originally going to do this in my SpeccyTrain demo ( https://github.com/mtg101/SpeccyTrain ) replacing the unrolled LDIs for the window drawing.

But... it feels a little trivial. Like I can basically copy an example like https://chuntey.wordpress.com/tag/double-buffering/ or even asking an LLM AI.

Then I thought I'd make a new demo or game that uses stack-based rendering. But I got caught up in the actual demo or game...

So I'm making this demo with some more interesting use of the stack rendering to properly learn how it works, before using it in a future demo or game.