This used to be a rite of passage for programmers of the time.

One example would be the advice given by Scientific American's A.K. Dedney's "Computer Diversions" Here's a 2010 reprint of a 1985 article: https://www.scientificamerican.com/article/mandelbrot-set/

And "Fractint" (a fast viewer for many fractal types) was my introduction to open source, although they called it "stone soup". https://en.wikipedia.org/wiki/Fractint

Fractint was, if not a killer app, really popular for EGA on PCs. Compute was getting fast enough at about the same time that the computations weren't too excruciating and EGA cards were the first mainstream graphics that Mandelbrot etc. sets looked decent.

I was there too. Plus at the time Mandelbrot was new, as new as Deepdream images are today.

So the Alto must pre-date Mandelbrot sets and therefore this demo is non-canonical, like playing Tetris on it, not possible at the time or even imagined.

This reminded me of an interview w/ Carl Sagan, Stephen Hawking, and Arthur C Clarke from 1988. Clarke demos the Mandelbrot set and is clearly very excited. If only they knew...

https://youtu.be/1srEEbB_vrI?t=18m31s

Hawking knows.

Google image did not disappoint

https://s-media-cache-ak0.pinimg.com/736x/7d/88/3f/7d883f900... https://images-cdn.9gag.com/photo/aX9BeN2_700b.jpg

The Alto was introduced in 1973, but was still available in the early 80s, so there is every possibility that someone wrote a Mandelbrot generator on it since it was discovered in 1980. However it is more likely that this happened on the Xerox Star which was around from 1981 and also after 1985 when the first popular Scientific American article about the set appeared...

… while in the same era Peitgen and Richter were publishing books with detailed Mandelbrot sets in full-colour plates. What computers were they using?

I worked in a books warehouse before college and two of their books had a little accident and ended up in the rejects bin along with some of my course texts. I lent the P and R books to someone and forgot who so actually bought them later on. They are amazing.

I also remember how short things like Iterated Function System plotters could be - eg a few dozen lines of BASIC could get you a complicated fern piccy in a few seconds on a 80286.

I suspect they had access to some decent Unix workstations with expensive displays. The quality of the plates was breathtaking - you can barely see the graduations in many of the images and they are totally smooth in most of them.

I've just had a massive hit of nostalgia - thanks!

I recall seeing full-colour real-time Mandelbrot set zooming and fractal landscape rendering on a Meiko Computing Surface (containing 32 or 64 Transputers, IIRC) at university, circa 1990. I studied Occam at the time but we weren't allowed to actually program the Transputers ourselves.

https://en.wikipedia.org/wiki/Meiko_Scientific#Computing_Sur...

They reference IBM labs. The Beauty of Fractal Images talks about an IBM 4361-5 with extended precision, and an IBM 4250 printer for one of the monochrome plates near the end of the book.

The Science of Fractal Images lists, as credits for the colour plates, these people and institutions: http://imgur.com/a/KSnDZ

A cousin, the 4341, was my first mainframe. That was the first time I was exposed to the concept behind pg's "beating the averages article": at a time most of my colleagues were writing dBase or COBOL code, I interned with people using Cincom's Mantis. It was the Rails of the 3270.

I remember their demos. Their secret sauce was in the algorithm, which somehow would spend little time on the featureless parts.

One simple way is to start with a largish square, say 8x8 pixels, and evaluate the Mandelbrot set at the corners. If you get the same color, paint the square in a single color. Otherwise split it in 4 smaller blocks, evaluating the set at a 3x3 grid (which is not really correct, the four squares don't actually have any corner in common, but it's twice as fast). Again if any small square has the same color at the corners, fill the block with one color.

One improvement for accuracy is, if you find all four corners have the same color (no matter if it's an 8x8 or 4x4 block), pick another pixel and iterate that one; if the color doesn't match, skip the optimization. That is more expensive, up to 25%, but it can avoid mistakes in the chaotic areas of the set.

And of course, the large cardioid in the center has an analytic expression, and you can skip pixels inside that area, or a conservative approximation of the area.

Yup - did that, and it was a lot faster on an Archimedes A310, I recollect minutes rather than hours and that was without the FPA unit.

It crazy how far computers have improved so this is the kind of thing you can do as a hobby project.

https://m.youtube.com/watch?v=0jGaio87u3A

I remember trying to do this on a 286 and it would take the better part of a day to do an EGA quality image. A friend at the time had a 386 and it seemed blazing fast, it would take only a few hours to do a 640x480 VGA image.

Now you can do this real-time on the GPU: https://www.shadertoy.com/view/4df3Rn