Are you 100% certain that these demos are meant to run on the A500 and not the A1200?
Then there's always the possability that the demos won't run on anything else than the specific setup it was developed on (read: lame programmer). There's heaploads of that stuff you know. Demos which only run with 512KB/1024KB/2048KB chipmem, with or without fastram, only works with 1.2/1.3/2.0 kick, won't work with HDD, etc.
Nearly (joke):
...only working 10% of the time and only if run off the programmers own floppy, in the same avr. temperature/moist conditions and by the programmer himself (if ever) :-) :-) :-)
Most sane people use UAE for those.
