perhaps the most significant milestone of the 1970s era of slr computerization was the 1978 release of the canon a-1, the first slr with a "programmed" autoexposure mode. although the minolta xd11 was the first slr to offer both aperture-priority and shutter-priority modes in 1977, it was not until the next year that the a-1 came out with a microprocessor computer powerful enough to offer both of those modes and add the ability to automatically set both the shutter speed and lens aperture in a compromise exposure from light meter input.