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US 4,301,516 AGranted
Bubble memory storage unit
AssigneeNCR Corporation
InventorWilliam C. Ellsworth
Life of this patent
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AssigneeNCR Corporation
InventorWilliam C. Ellsworth
Estimating the term…
A magnetic bubble domain memory device is provided that includes a magnetic domain data chip having a major-minor loop organization with on-chip firmware providing redundancy information enabling the use of the chip even though one or more defective minor loops may be present thereon. One of the pages is written in the minor loop, where a page is defined as a common bit position in each of the plurality of minor loops, with a series of magnetic domains having an odd total number. The next succeeding page in the minor loops contains a series of magnetic domains and voids which are representative of the loop numbers of defective minor loops on the chip with the remaining pages in the minor loops having an even number of magnetic domains contained in each of the pages. Collectively, the pages containing the odd and even number of magnetic domains together with the page containing the map of the defective minor loops comprise the on-chip firmware providing redundancy information. This magnetic domain structure is capable of screening out defective minor loops in the read and write operations, and enables synchronization of the magnetic domain device such that a selected page of data may be readily accessed from a plurality of minor loops when desired.
A magnetic domain memory device comprising:
A magnetic domain memory device comprising:
A method of accessing odd-chip redundancy date to insure data credibility for a magnetic domain memory device having a major propagation path operably aligned with a plurality of minor loops of which at least one is defective, wherein data stored in the minor loops on pages defined by corresponding common bit positions in each of said plurality of minor loops includes a first page having a first predetermined number of magnetic domains, a second page containing the redundancy data identifying the defective minor loops and a plurality of third pages each containing a second predetermined number of magnetic domains, said method comprising reading and evaluating each page for said first predetermined number of magnetic domains and storing the redundancy data located in the next succeeding page for use in evaluating the data stored in the minor loops in response to the finding of said first predetermined number of magnetic domains in one of the pages.
A method of synchronizing a magnetic domain memory device having redundancy data stored in one of a number of pages of a plurality of minor loops operably aligned with respect to a major loop, wherein each page of data is respectively defined by corresponding common bit positions in each of said plurality of minor loops, said memory device having a first page of data containing an odd number of magnetic domains, a second page of data located adjacent said first page of data and containing a series of magnetic domains and voids representative of the loop numbers of defective minor loops and remaining pages of data containing an even number of magnetic domains, siad method comprising:
Dependencies are inferred from the claim text.