I discuss the requirements for optical and optoelectronic devices for large-scale use in digital processing systems. Optics has many potential advantages, especially in helping communications within processors. It is difficult to make optical logic devices because few nonlinear effects are large enough and because most device concepts cannot satisfy the qualitative requirements for digital logic. Quantum well symmetric self-electrooptic-effect devices are now good enough optical logic elements for systems experiments with free-space optics. There are also future prospects for large-scale integration of quantum well optical devices with electronics. This may eventually allow the best of both electronic and optical features for better system performance.