I had a blog article about the entire mess that was often confused (there was actually three modes): http://yuhongbao.blogspot.ca/2009/09/mac-os-xs-64-bit-modes

I had a blog article about the entire mess that was often confused (there was actually three modes): http://yuhongbao.blogspot.ca/2009/09/mac-os-xs-64-bit-modes.html http://yuhongbao.blogspot.ca/2009/09/mac-os-xs-64-bit-modes....