Patent US2931691A successfully refreshed from Google Patents.
US2931691A
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Magnetic drum memory system
Assignee: Northrop Grumman Systems Corp
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Filing: 1956-08-20
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Granted: 1960-04-05
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Expires: 1976-08-20
Abstract
No abstract record available.
Inventors
- 👤 Daniel L Curtis
- 👤 Robert B Larsen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 11:20
CPC Classifications
G; G11; G11B; G11B25/00; G11B25/02; G11B5/00; G11B5/127; G11B5/17; G11B5/48; G11B5/54; G11B5/55; G11B5/5591; G11B5/58
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2694192A
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US2705640A
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US2838614A
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US2806757A
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US2772135A
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US2820688A
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US2802905A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1963-04-05 | 1963-10-05 | 1964-04-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1967-04-05 | 1967-10-05 | 1968-04-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1971-04-05 | 1971-10-05 | 1972-04-05 | $7700.00 | Window Closed / Lapsed |