Z5
It was actually that very intro which inspired me. I wrote all this code way back sometime around 1995 in my teens and I was hardly a top coder, all the stuff I wrote I had learned from trial and error and sometimes from disassembling the intros I could download from the local BBS. I remember it took me a while before I finally figured out how they had done this effect and how simple it really was, two sets of four bitplanes with a radial pattern and the 16*16 texture written into the 256 color registers. Obviously I had to try it out with the Commodore logo too. Sweet nostalgia.
NWM
http://zb.stolendata.net/amicode.zip
I uploaded these routines and some other stuff above. The code isn't fancy or elegant, and it probably won't run on anything but an unexpanded A1200, but you're more than welcome to play around with it.
Thanks for your comments!