Reid’s For Fun


My personal blog for what interests this computer guy. Web development, LEGO ray tracing, ZX81 retro computing, writing and photography.


Wasting Time Watching Circles in This ZX81 Demo

Circles, ZX81 Screenshot, 2022 by Steven Reid

I ran across a ZX81 forum post showing a fast way to print a circle in BASIC. It was based on an article for the Atari back in 1983. I was surprised how fast the routine was and wondered how it would in assembly. Long story short, I built a screen saver for the ZX81. Sure, the ZX81 really didn’t need one, but the circles are fun to watch.