The inclusion of a storage hierarchy represents one of the major advances in system organization present in the Model 85. Although the concept of a storage hierarchy is not new, the successful implementation of a nanosecond/microsecond level of hierarchy was inhibited until now by the lack of a suitable technology. As implemented in the Model 85, the fast monolithic storage physically integrated with the CPU logic yields the desired machine speed, while the large core storage yields the desired storage capacity, the combination being transparent to the user. It is likely that with future progress in technology this nanosecond/microsecond hierarchy is not merely an innovation that worked out well for the Model 85, but rather it is a fundamental step forward that will be incorporated into most large systems of the future.