Laurence L. Rosier

The use of bubble lattices for information storage

A new approach to bubble memories, called a bubble lattice file (BLF), is described. This approach employs a periodic bubble lattice to define bit positions while the information is contained in the wall structure of the bubbles. The principal advantage of the BLF is the increased storage density, sixteenfold when the resolution capability of the fabrication process is the limiting factor. The device functions required for the BLF, including accessing and write/read operation, are described. Significant differences between BLF and the T‐I bar bubble memories are discussed.

Column access of a bubble lattice: column translation and lattice translation

The use of a regular array. or lattice, of magnetic bubbles for the storage of information requires two kinds of functions: the read-write functions involving the generation and discrimination of bubbles with different wall structures, and the access functions involving the insertion and removal of bubbles at selected locations in the lattice. In a column-accessed bubble lattice device, accessing is accomplished by first translating the lattice to position the desired column of bubbles in an input-output access channel and then translating this column along the channel to a detector area outside of the lattice while simultaneously introducing new bubbles from a generator area at the other end of the channel. An analysis of the influence of device design parameters on access rate indicates that the most important parameters are the column translation rate and lattice capacity. A device is described that was designed to study the translation of a lattice of bubbles and of a single column of bubbles within the lattice. Quasistatic operating margins and dynamic measurements of this test device indicate that the column-access configuration provides feasible means for the rapid access of bubbles from a lattice.

Bubble lattice translation—experimental results

One of the primary functions required for a bubble lattice device is the translation of the lattice for accessing information. This paper describes the results of a test device designed to study the translation of a bubble lattice. The design utilizes buffer regions at each end of the lattice. The buffer regions contain parallel stripe domains aligned along the direction in which the stripe domains aligned along the direction in which the lattice is translated. The lattice initialization procedure involves first applying an a.c. in‐plane field to form an array of parallel stripe domains. The stripe domains are then cut into bubble domains by conductor lines fabricated on the bubble material. The domains within the active area of the device are isolated from the domains in the surrounding area by selectively ion milling the garnet material. A 12 column X 28 row lattice was quasistatically translated by applying bipolar current pulses to pairs of conductor lines placed so as to provide a driving force on every fourth column of bubbles in the lattice. Using a 2.5 Oe peak, 1 MHz bias modulating field to minimize coercivity effects the minimum current required to translate the lattice was 3 mA which corresponds to a power dissipation in the condutor lines of 165 nW/bubble. The bias field operating margin at 3.5 mA was 10.5 Oe±25%.One of the primary functions required for a bubble lattice device is the translation of the lattice for accessing information. This paper describes the results of a test device designed to study the translation of a bubble lattice. The design utilizes buffer regions at each end of the lattice. The buffer regions contain parallel stripe domains aligned along the direction in which the stripe domains aligned along the direction in which the lattice is translated. The lattice initialization procedure involves first applying an a.c. in‐plane field to form an array of parallel stripe domains. The stripe domains are then cut into bubble domains by conductor lines fabricated on the bubble material. The domains within the active area of the device are isolated from the domains in the surrounding area by selectively ion milling the garnet material. A 12 column X 28 row lattice was quasistatically translated by applying bipolar current pulses to pairs of conductor lines placed so as to provide a driving force on ev...