Magnetic bubbles—An emerging new memory technology

Magnetic bubbles-an emerging storage technique-promise to bridge the capacity-data retrieval time gap left vacant by magnetic core and semiconductor devices on one side and the electromechanical magnetic tape and disk on the other. Improvements in bubble materials, circuit processing, and device design have advanced bubble technology to where it is a solid candidate for applications requiring 10 6 -10 8 bits and retrieval times less than 0.005 s. Bubble chips as large as 65 kbits are currently under development. In this paper, the reader is first introduced to the topics of bubble statics and bubble dynamics, including a discussion of hard bubbles. Next, the operation of bubble devices such as propagation, generation, detection, and replication is described, as well as chip organizations using these functions. Temperature plays an important role and its effect on domain generation and data longevity is described. Fabrication techniques for bubble chips used in prototype mass memory modules and an experimental memory for a repertory telephone are given as are the overall systems' performance. Details of a 32-pin dual in-line bubble package are described. Finally, some predictions into the future are attempted for this technology. This discussion includes self-structuring propagation of bubbles and the bubble lattice file memory concept.