Rockwell International Corporation

National Semiconductor Corporation

Peter K George

Tsutomu Kobayashi

Isoris S Gergis

Thomas R Oeffinger

Saleem Akhtar

A field-access bubble memory chip has a plurality of permalloy elements overlying an insulating layer. The permalloy elements are configured and positioned to define a plurality of paths for propagating magnetic bubbles under the influence of a Z bias magnetic field and a rotating XY magnetic drive field. A first portion of the paths are located in control function areas of the chip and a second portion of the paths are located in a storage area of the chip. The period of the permalloy elements in the control function areas is substantially greater then the period of the permalloy elements in the storage area. The thickness of the insulating layer immediately beneath the permalloy elements is less in the storage area than in the control function areas. This difference in thickness is sufficient so that the propagation margins for magnetic bubbles in the control function areas and in the storage area are substantially equal. Thus the bit density in the storage area can be significantly increased by reducing the period of the elements therein without any net reduction in the overall margin of the chip.

Bubble memory with enhanced bit density storage area

A bubble memory chip includes a plurality of data loops, some of which may be defective, for storing magnetic bubbles representative of data therein. A serial-parallel input propagation path and a parallel-serial output propagation path are provided for propagating bubbles to and from the data loops. A plurality of spaced apart permalloy disk elements are provided, each adapted for having a single bubble circulated thereabout in the presence of an in-plane rotating magnetic drive field. A stream of bubbles representative of an error map indicating which of the data loops are defective is loaded onto and read from the disk elements to initialize the memory. A plurality of gates permit the bubbles of the error map to be transferred between an error map propagation path and the disk elements in parallel fashion upon pulsing of an adjacent control conductor. The potential for data scrambling in the error map is eliminated. Power consumption and access time are reduced in connection with reading and propagating the error map through the detector to initialize the memory.

Bubble memory with on chip error map storage on permalloy disk elements

In a bubble memory, propagation elements are configured so that shorts between adjacent elements as a result of fabrication inaccuracies do not destroy their poles and create barriers to bubble propagation. In designing the bubble memory, the gaps can thus approach the resolution limit of the photolithography, resulting in a higher storage density and a reduced operating drive field. In one embodiment permalloy chevrons which overlie a garnet film have opposing side edges defining a gap therebetween which increases in width moving in a direction away from the poles.

Bubble memory with increased gap tolerance between propagation elements

In a field-access magnetic bubble memory X and Y coils encircle the chip for providing the rotating XY magnetic drive field when conventional drive signals are applied thereto. At least one of the coils is non-uniformly wound to provide a first predetermined magnitude of the drive field in first predetermined chip areas and a second lesser predetermined magnitude of the drive field in a second chip area. In the embodiment disclosed the chip has a dual-block replicate architecture with gates and bubble detectors requiring a relatively high drive field located in peripheral edge areas at the bottom and top of the chip. A plurality of data storage loops requiring a relatively low drive field are located in the medial portion of the chip. The outer layer of the Y coil is non-uniformly wound to provide a gap in registration with the medial area of the chip. As a result, the magnitude of the drive field is higher in the peripheral edge areas than in the medial storage area, making possible a reduction in coil power consumption.

Bubble memory having non-uniformly wound Y drive field coil

The invention is directed to continuous (gapless) propagation structures for use with magnetic bubble domain devices. The gapless structures are arranged so that magnetic bubbles will propagate therealong without a significant change in size or diameter of the bubble. In addition, the structures are configured so that the bubbles will propagate in a preferred direction without ambiguity.

Continuous propagation structures

Disclosed is a magnetic bubble memory that includes a plurality of minor loops for storing bubbles representative of data therein, and a pair of minor loops for storing bubbles representative of an error map therein. The error map is selectively written into and read from only one loop of the pair. The other loop is redundant and improves chip yield. A serial-parallel bubble propagation path connects all of the loops to a bubble generator. This path includes a predetermined number of bubble propagation elements between the transfer-in gates for the pair of loops. Proper choice of the number of propagation elements enables the error map to be selectively written into/read from only one loop of the pair with only a single control line.

Bubble memory with redundant on chip error map storage loops

There is provided a switch which is useful in magnetic bubble domain devices. The switch can be used to replicate, transfer or annihilate any bubble domains in a magnetic bubble domain system. The switch comprises a 'BOOMERANG' shaped element which is disposed adjacent to two juxtaposed magnetic bubble domain propagation paths. A re-entrant current path conductor is integrally connected to the boomerang shaped element and associated with at least one of the propagation paths whereby magnetic bubble domains can be stretched, cut, annihilated or the like in response to a control current signal. Optional bar shaped elements are associated with various components of the switch in order to improve the operating characteristics of the switch.

One level switch for magnetic bubble domain devices

There is provided a switch which is useful in magnetic bubble domain devices. This switch can be used to replicate, transfer or annihilate bubble domains in a magnetic bubble domain memory system. The switch comprises a half-disk (or pick-axe) shaped element which is disposed adjacent to two juxtaposed magnetic bubble domain propagation paths. A re-entrant current path conductor is integrally connected to the half-disk element and associated with at least one of the propagation paths whereby magnetic bubble domains can be stretched, cut, annihilated or the like in response to a control current signal. Optional bar elements are associated with the half disk elements of the switch to improve the operating characteristics thereof.

One-level switch for magnetic bubble domain devices

There is provided a memory system, for example, a magnetic bubble domain memory, which includes an exchange stack buffer memory between a main storage area and other portions of a bubble domain chip organization. The buffer memory includes a plurality of magnetic areas, such as discs, arranged in an ordered array between the main storage area and the remainder of the chip organization. Control conductors are arranged to interconnect each row of magnetic areas with an adjacent row of similar areas, or with portions of the main storage area, or with the remainder of the chip organization circuit. Means are provided to supply signals to the control conductors to selectively transfer information from a row of magnetic areas to one of the adjacent areas.

Exchange stack buffer memory

There is described a bubble domain field access device component for providing continuous generation of a stream of bubble domains. The device is in the nature of a passive generator which is preferably constructed using one-level processing. The device uses multiple chevrons (chevron columns) which have the advantages of inherent redundancy, reduced gap tolerances and wide propagation margin. The structure comprises, generally, a rectangular seed plate arranged as a 90.degree., multiple-chevron, corner portion.

Multiple chevron passive generator

There is disclosed an improved circuit element or structure for use in propagation of magnetic bubble domains. The improved circuit element permits a more desirable gap-to-period ratio than conventional element patterns. The improved circuit element provides portions thereof which are substantially parallel to similar portions of adjacent, similar circuit elements. As a consequence, the magnetic poles developed in the adjacent circuit elements by the application of the in-plane magnetic field are substantially identical at a given time thus facilitating interelement transfer. The circuit element structures are arranged in various propagation paths and operational components. Propagation paths and inter-propagation path elements are described.

Gap tolerant bubble domain propagation circuits

A plurality of stretcher detector segments are connected in series whereby detector signals generated when a bubble passes thereby are added together. Each of the stretcher detector segments is disposed an identical propagation distance away from passive replicators wherein bubbles are replicated from a propagation path and applied, simultaneously, to the stretcher detector segments. The stretcher detector segments are arranged to include both dummy and active portions thereof which are arranged to permit the geometry of both the dummy and active portions of the segment to be substantially matched.

Multi-segment detector

A passive replicator comprising a plurality of elongated bars interposed between an input propagation path and a plurality of output propagation paths.

Passive replicator

There is described an improved switching device for use in magnetic bubble domain systems. In this device, chevron propagation paths are utilized. A pair of substantially parallel conductors are interconnected at appropriate locations via the chevrons in the respective propagation paths. The pair of conductors permits reduced amplitude requirements in the control current signal. In addition, a return path for the current signal is provided to simplify interconnection in major/minor loop chip configurations. The chevrons are arranged such that the apex of one chevron group is contained between the pair of conductor lines. The ends of adjacent chevron groups in another propagation path are disposed between the pair of conductor lines. Consequently, the magnetic bubble domain 'sits' on the chevron ends longer whereby wider phase margins during a transfer operation are achieved. Annihilation of magnetic bubble domains can be achieved by reversing the current direction.

One-level magnetic bubble switching device

A block oriented random access memory (BORAM) magnetic bubble domain system which provides increased throughput of information and reduced access or read time for the same information as compared to existing major-minor or decoder accessed chip organizations which it is designed to replace.

Growing community of inventors

Placentia, CA, United States of America

Peter K George