Two loops, a sine and a cosine, each step feeding the last: a handful of maths that draws a twisting orb of tangled strands. Here it is in full colour, or as live ZX Spectrum BASIC, with the knobs on the outside.
In February 2020 a generative artist who posts as yuruyurau shared a tiny Processing sketch that drew a glowing, swirling orb out of nothing but sines and cosines. It spread among retro-computing fans, who began porting it to every old machine they owned. In November 2022 Paul Dunn, who writes the SpecBAS interpreter, posted a version in a few lines of ZX Spectrum BASIC, and Lars Brinkhoff collected ports for everything from JavaScript to a PDP-10 driving a colour oscilloscope.
The listing on the page is real Spectrum BASIC, and it changes as you move the knobs. Switch to Spectrum and tick Real 48K speed to watch it draw the way a 1982 Spectrum would, a few dozen dots a second; a whole frame takes about two minutes.
