It is based on an algorithm published on pouet in 2021. It (v4) uses 16 colors and interlaced 256x424 video mode. Generated pictures are 128x256 raster images. It is very likely that this algoritm implementation is the fastest known Mandelbrot set computation routine for the z80. There is another variant (v5) of this program which uses non-interlaced 256x192 video mode. This variant shows rotated 256x128 images, it is slower because it uses the VDP less effectively.
The both variants are available on the packed disk image.
There are also fullscreen variants on the disk image:
|* 512x212, 16 colors (v5)|
|* 512x424, 16 colors, interlaced (v5)|
|* 256x212, 256 colors (v5)|
Several samples of fullscreen images are shown below.
512x212, 16 colors
512x424, 16 colors, interlaced
256x212, 256 colors
Sources are available on github.