Ken Shirriff writes:
When I found out that the Computer History Museum has a working IBM 1401 computer, I wondered if it could generate the Mandelbrot fractal. I wrote a fractal program in assembly language and the computer chugged away for 12 minutes to create the Mandelbrot image on its line printer. In the process I learned a bunch of interesting things about the IBM 1401, which I discuss in this article.
Details at Ken Shirriff’s blog.