Embedded memory with security row lock protection
First Claim
Patent Images
1. A semiconductor memory comprising:
- an array of first memory elements including bit lines coupled with corresponding columns of elements in the array and word lines coupled with corresponding rows of elements in the array, each of the first memory elements holding data, said array further including a security row of second memory elements coupled to a corresponding security word line, each of the second memory elements being coupled to the bit lines of the array of first memory elements, said second memory elements being programmed in a first mode of operation to allow the data in the first memory elements to be read, said second memory elements being programmed in a second mode of operation to prevent the data in the first memory elements from being read; and
means for selecting the security row to operate in either the first mode of operation or the second mode of operation.
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Abstract
A memory device having a memory array of nonvolatile memory elements also includes one or more security rows (or columns) of security bits that can be programmed to a locked status. External memory access requests are processed by first reading the corresponding security bit. If the requested row or column is locked, a default zero value is returned. Only external requests of unlocked locations, and all internal access requests, return the actual memory contents. Security bits can be erased (unlocked), but the secured contents of the locked row or column is also erased at the same time.
16 Citations
14 Claims
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1. A semiconductor memory comprising:
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an array of first memory elements including bit lines coupled with corresponding columns of elements in the array and word lines coupled with corresponding rows of elements in the array, each of the first memory elements holding data, said array further including a security row of second memory elements coupled to a corresponding security word line, each of the second memory elements being coupled to the bit lines of the array of first memory elements, said second memory elements being programmed in a first mode of operation to allow the data in the first memory elements to be read, said second memory elements being programmed in a second mode of operation to prevent the data in the first memory elements from being read; and
means for selecting the security row to operate in either the first mode of operation or the second mode of operation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of operating an embedded semiconductor memory comprising:
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having security lock protection responsive to an external access request to said memory; and
disabling external access to a memory array row whenever a security bit in a security row indicates a locked status, and otherwise enabling access to the memory array. - View Dependent Claims (11, 12, 13, 14)
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Specification