Semiconductor memory device
Patent 4942556 Issued on July 17, 1990. Estimated Expiration Date: 
July 10, 2009. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
July 10, 2009. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesPaired least recently used block replacement system Address mapping for memory Block associative memory Simplified cache with automatic update Quasi content addressable memory Patent #: 4758982 Inventors
AssigneeApplicationNo. 377181 filed on 07/10/1989US Classes:365/200, Bad bit365/49, ASSOCIATIVE MEMORIES365/168, Ternary365/185.2, Reference signal (e.g., dummy cell)365/207Differential sensingExaminersPrimary: Fears, Terrell W.Attorney, Agent or FirmInternational ClassG11C 013/00Foreign Application Priority Data1986-04-23 JPAbstractIn a defect relieving technology which replaces defective memory cells of a semiconductor memory device by spare memory cells, use is made of an associative memory. Address information of a defective memory cell is stored as a reference data of the associative memory, and new address information of a spare memory cell is written down as output data of the associative memory. A variety of improvements are made to the associative memory. For instance, a plurality of coincidence detection signal lines of the associative memory are divided into at least two groups, and one group among them is selected by switching means. Reference data of the associative memory comprises three values consisting of binary information of "0" and "1", and don't care value "X". The associative memory further includes a plurality of electrically programable non-volatile semiconductor memory elements. | |
