Improving the performance and extending the utility of information processing requires access to ever larger volumes of data. Thus, the impact of progress in storage technology on the overall growth of the information processing industry is immense. By advances that continually reduce the cost of storage it becomes feasible to develop and place more and more applications on computer systems by permitting both a larger system data base and more sophisticated control and applications programs. Unfortunately, the term "mass storage" has no precise technical meaning, being all too frequently used to describe on-line peripheral storage of a size bigger than a user currently believes he can justify. Once the user's system is upgraded to that level, however, as technical advances over time allow capacity to be increased for a fixed cost, this amount of storage is barely considered adequate, much less "mass." In discussing hardware, the term is most commonly associated with mechanical storage devices. While solid-state memory continually provides more and more bits per chip, the rate at which storage capacity can be absorbed grows even faster, and thus it seems electronic memories will never eliminate the use of auxiliary storage devices. As storage costs decrease, applications expand, the market grows, and product volume increases; the resulting cost reductions in turn reinforce the cycle. In addition, it then becomes feasible to increase investment in technology, which results in a further improvement in cost/performance. It is thus important to understand storage technology trends if one is to anticipate the future.