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High reliability content-addressable memory using shadow content-addressable memory
Assignee: GlobalFoundries Inc
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Filing: 2003-05-06
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Granted: 2004-02-03
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Expires: 2023-05-06
Abstract
Abstract A high-reliability content & addressable memory using a shadow content-addressable memory (CAM) array in parallel with a primary CAM array to increase the reliability of CAM searches. The reliability of CAM searches has been less than desired because of random environmental influences that corrupt data. The shadow CAM is written, read, and searched in parallel with the primary CAM. The search results from the parallel searches are compared and, if identical, are declared valid. If the search results are not equal, corrective action is initiated. The high-reliability content-addressable memory may be used with or without priority encoders.
Inventors
- 👤 Kevin A. Batson
- 👤 Geordie M Braceras
- 👤 Robert E. Busch
- 👤 Gary S. Koch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 14:00
CPC Classifications
G; G11; G11C; G11C15/00
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
100 words
A shadow content-addressable memory apparatus comprising: a first content-addressable memory and a second content-addressable memory having, respectively, a first array of content-addressable memory and second array of content-addressable memory configured for writing, reading and searching in the first and second arrays in parallel; comparison circuitry coupled to the first and second CAM and configured to compare a search result from the first array of content-addressable memory with a search result from a second array of content-addressable memory; and circuitry configured to generate an output responsive to the first and second search results to indicate whether the search results are equivalent.
Claim 2
Dependent Claim
100 words
A shadow content-addressable memory apparatus comprising: a first content-addressable memory and a second content-addressable memory having, respectively, a first array of content-addressable memory and second array of content-addressable memory configured for writing, reading and searching in the first and second arrays in parallel; comparison circuitry coupled to the first and second CAM and configured to compare a search result from the first array of content-addressable memory with a search result from a second array of content-addressable memory; and circuitry configured to generate an output responsive to the first and second search results to indicate whether the search results are equivalent.
Claim 3
Dependent Claim
24 words
The apparatus of claim 1 wherein arrays of content-addressable memory comprise content-addressable memories with address spaces having a non-identity one-to-one mapping to each other.
References Cited (Backward Citations)
US3789204A
Cited
US4692900A
Cited
US5034919A
Cited
US5574883A
Cited
US5568434A
Cited
US5717885A
Cited
US5918047A
Cited
US5812469A
Cited
US6046946A
Cited
US5912836A
Cited
US6175514B1
Cited
US6362993B1
Cited
US6373739B1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2007-02-02 | 2007-08-04 | 2008-02-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2011-02-02 | 2011-08-04 | 2012-02-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2015-02-02 | 2015-08-04 | 2016-02-03 | $7700.00 | Window Closed / Lapsed |