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Record Recovery in an Electronic Drum

IP.com Disclosure Number: IPCOM000089351D
Original Publication Date: 1977-Oct-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 4 page(s) / 48K

Publishing Venue

IBM

Related People

Kinberg, CC: AUTHOR

Abstract

This article describes a method and apparatus for the recovery of data distributed among m rows of n electrically independent storage elements, each element containing bit-modulated bubbles. The m x n elements are arranged in a matrix array. An (n + 1)st element in each row, e.g., the ith row, stores the result of exclusive ORing the bits from the N other row elements. Consequently, data from an inaccessible jth element in the kth row can be recovered by exclusive ORing the kth row contents of the N remaining row elements.

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Record Recovery in an Electronic Drum

This article describes a method and apparatus for the recovery of data distributed among m rows of n electrically independent storage elements, each element containing bit-modulated bubbles. The m x n elements are arranged in a matrix array. An (n + 1)st element in each row, e.g., the ith row, stores the result of exclusive ORing the bits from the N other row elements. Consequently, data from an inaccessible jth element in the kth row can be recovered by exclusive ORing the kth row contents of the N remaining row elements.

A multiple tape system in which an entire record is written on the same device has been described [1]. Redundancy data is generated on the N + 1 tape by exclusive ORing data transversely across the N electrically independent tapes. In order to recover a record, it is necessary to replay the N tapes at least to the point where the record of interest can be reconstituted.

The subject device is described in terms of a storage device based on field driven bubbles. Advantage is taken of the fact that all bubbles driven from the same field move in synchronism, thereby ensuring a fixed time and space relationship between bubbles in different areas or devices. For the purpose of this discussion a physical record is the set of all bits that can be accessed (stored or read) simultaneously. A data record will consist of one or several physical records. Corresponding bits of different physical records stored on different devices (hoops) are XORed, and the result is stored in a separate device. It represents an advance over the prior art since (1) recovery is fast and can be automated, (2) all bits associated with a given redundancy datum are implicitly identified (3) the checking mechanism is independent of data record length and data contents, and (4) the techniques are extendable to any storage technology where space and time relationships between physical records are controllable. An example is the class of devices based on bubble lattices described in [2].

The implementation of an electronic drum has been described which was intended to provide an extension of main memory in computer systems. Since such a device would permit the conversion of a volatile memory into a much larger nonvolatile memory system, it is important that the reading/storing/writing processes be made as reliable as possible. This device permits automatic correction or recovery of a defect physical record. It is assumed that the status of a physical record in each device (hoop) is monitored via parity checks or other means. Within the context of this disclosure, physical ""record'' refers to the quantum (8 bytes) appearing on the input or output ports of a "hoop". It is a physical and not a logical entity.

In the figure, a ""barrel'' is shown in the shape of a matrix in which the elements are hoops. All hoops in a row are driven from the same pair of field drivers, which means that the data in the four hoops can...