It is based on an algorithm published on pouet in 2021. There are two variants of this generator. One generates 512x256 monochrome raster images. Actually only 128x256 Mandelbrot dots are computed and plotted but 4x1 texture bricks are used to simulate 8 colors. Another generates 256x128 raster images using 16 colors. It has to rotate the images and this slows down the video performance much. It is likely that this algoritm implementation is the fastest known Mandelbrot set computation routine for the 68000.
An archive with the executables is here: just run
MA-RO under TOS to get a Mandelbrot gallery.
You can also try
MA-FS to get a fullscreen variant (320x200, v2) that uses 16 colors, and
MA-FS-MO to get a fullscreen monochromatic variant (640x400, v1). The next images are generated by these program.
Sources are available on github.