[raydiak]

I don't pretend to know anything about HP calc hacking (did a little TI BASIC for fun, that's not even remotely similar). But doesn't this come up in all kinds of daily situations, graphical or otherwise? You only recalculate and update the parts that may have changed. I assume this is similar to why Zelda on my original black and gray GameBoy as a 90s kid was arranged into scenes with few moving elements, so it didn't have to recalculate rendering for the entire screen during action.

[bobmcnamara]

The demo video shows full screen scrolling, in which the entire screen updates smoothly.

Also, LCDs require periodic refresh, so partial LCD updates require framebuffer memory somewhere, often in the display controller built into the LCD panel or module, or less commonly into the pixels themselves. It's possible there's a frame buffer hiding somewhere, but plenty of systems don't have one, so the only option is always updating the entire LCD every refresh.

[raydiak]

The demo shows deterministic physics with no input, which gives me various suspicions. But I agree, it is clearly updating most or all of the screen for every frame