Volume 17 of Advances in Computers treats several topical, significant areas of major interest in the very dynamic computer field. Since the first volume of this serial publication appeared in 1960, computer and information technology and applications have experienced a number of major revolutions, each changing the field significantly. The current situation, primarily involving microprocessing and microelectronics, is no exception, and changes are taking place at an ever increasing rate. Over the years, Advances in Computers has attempted to cover the major areas of interest in computer and information science and technology, accurately presenting some of the more important trends.