In the early 90s I wrote a Mandelbrot Set generator in 68000 assembly language on the Atari ST. The 68000 processor didn't have any floating point arithmetic so I wrote a set of fixed point arithmetic routines with precision ranging from 16bit, 24bit and 32bit. These all had 8 bits for the integer with the remaining holding the fraction part.

I managed to find a copy of the program and got it to load in an emulator. The Atari takes around 10 seconds to draw, and only uses a 200x200 window. A couple of years ago, I wrote a Java version which works as an ImageJ plugin. This version is much faster (0.07s for a 800x600 image), which works out as 1700x faster than the Atari, despite only being clocked 300x faster. Processor design improvements and hardware floating point probably account for much of this increase.

The atari version can be downloaded here. The ImageJ version is available here (ImageJ and Java8 required - an older version which works with Java6 is also available)