My D200 meters in A mode with an AI lens. It doesn't display the correct aperture number, unless I enter the lens focal length and maximum aperture under "Non-CPU lens data," because the body doesn't know the absolute aperture, only the number of stops between wide open and stopped-down. But it exposes correctly and the shutter speed changes as I turn the aperture ring. Film AF bodies that have an aperture sensing ring should all work with an AI lens in A mode as well. That's why Nikon put the sensing ring there. Some of the later lower end film AF bodies lack the sensing ring, such as the N65.