The 1 MB mod makes the expansion look like chipmem for the OS - however, if you've got an old Agnus in place, there's no way this would work properly as the registers are too small to address the correct data. Screen corruption, data corruption on floppies(!), Copper runaways and complete memory corruption when using the Blitter are bound to happen.
8375 is the most ambiguous labeling CSG used; there are various pinouts under that number. There was a good thread here comparing the different versions 1-2 years ago; BBoAH isn't too acurate in that respect. The A600 version is the same as the A500+ one, but it doesn't work in an older A500 without heavy modifications.
