Resident Evil 3 and mod chip
 

Why does re3 work with an external chip when booted with a demo but won't work with internal chip.I can't find anywhere saying that it is protected and if someone could tell me if a boot disk would help I would be gratefull if they can tell me where to get a reliable one.Ta in advance.

Like all copied games an internal modchip is a must... forget the swap disk method or boot disks, these are a really bad way of getting games to work.
It looks like RE3 requires a protection fix patch, this can be obtained from:
####://63.217.26.28/psx/psx_patches.shtml
apply the patch to the image of RE3. Full instructions on how to do this are given at the site. Get cdrwin first if u havnt already.