Digital memory and storage technologies occupy a dominant position in electronic data processing: They are intimately interwoven with almost all aspects of a data processing system, be it the control processing unit, the peripheral devices or the program and data storage. In this context, memory and storage is one of the most essential design parameters that determine performance and cost efficiency of the entire system to a very high degree. Beyond the field of electronic data processing, digital memory and storage fmd ever­ widening application in the areas of control and measurement techniques, in digital communication and switching, and lately, even in the area of the consumer electronic market. This explains, why since the beginning of the computer age, digital memory and storage are finding ever increasing attention in research and development. Of the many different memory and storage technologies investigated for application, only very few survived in the tough economic cost/performance struggle. This process still continues: Semiconductor memories have almost completely replaced the ferrite core memories. For the "gap" in cost and performance between memory and storage - which is of growing importance for systems throughput, particularly for query and database systems - very promising proposals, such as charge coupled devices and magnetic bubble memories appear. For very high data volumes, devices with automatic storage media transport have been conceived and ...