dont use the starndard format commands
use a special zip-drive one instead
download stuff from aminet - there is a site on the web for zip drives on the amiga - ill see if i can post a link soon...
...
ive actually tricked the thing into thinking a Z250 disk was a Z100!! and i used it in windows to try to reformat it to Z100, guess what? windows thought it was 100meg too!! :-D