Someone a while back was asking how to do copper effects.
For those who don't know, the "copper" was the name of a very simple but powerful graphics coprocessor on the Amiga. It had a very small list of commands available to it, having to do with changing color during scanline operations. It also allowed some other strange idiosyncrasies like having different resolutions at different vertical positions on the screen, something unique to the Amiga as far as I know.
Of course, like everything on the Amiga, the Copper was pushed beyond any sane limits by the demo scene, who did things with it that it was never designed to do.
I often wonder why the demo scene don't push limits of new hardware the way they used to. Perhaps because they don't need to anymore to achieve beautiful effects, but as amazing as they are, people seem to be resting on their laurels to some extent and not continuing to really push the technology.
Probably because they're obsessed with ancient hardware like Spectrums, and effects that were already played out in 1989...
Source removed; not everyone has blitz installed. Sorry to be a bother