Memory module with reduced access granularity
First Claim
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1. An apparatus that exchanges data with a memory controller over a data path having a width, the apparatus comprising:
- a first rank of memory;
a second rank of memory;
the first and second ranks of memory each operable to communicate data with the memory controller over the data path;
where each of the first rank of memory and the second rank of memory are operable in a selective one ofa rank-wide access mode, in which the first rank of memory and the second rank of memory exchange first and second data respectively at mutually exclusive times with the memory controller, where the first and second data each occupy more than half the width of the data path, anda sub-rank access mode, in which a first subrank of the first rank of memory and a first subrank of the second rank of memory exchange third and fourth data, respectively, at mutually exclusive times with the memory controller over a first subset of the width of the data path, and in which a second subrank of the first rank of memory and second subrank of the second rank of memory exchange fifth and sixth data, respectively, at mutually exclusive times with the memory controller over a second subset of the width of the data path, the third, fourth, fifth and sixth data each occupying no more than half of the data path width, the third data associated with an independent memory command from the fifth data and the fourth data associated with an independent memory command from the sixth data.
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Abstract
A memory module having reduced access granularity. The memory module includes a substrate having signal lines thereon that form a control path and first and second data paths, and further includes first and second memory devices coupled in common to the control path and coupled respectively to the first and second data paths. The first and second memory devices include control circuitry to receive respective first and second memory access commands via the control path and to effect concurrent data transfer on the first and second data paths in response to the first and second memory access commands.
199 Citations
21 Claims
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1. An apparatus that exchanges data with a memory controller over a data path having a width, the apparatus comprising:
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a first rank of memory; a second rank of memory; the first and second ranks of memory each operable to communicate data with the memory controller over the data path; where each of the first rank of memory and the second rank of memory are operable in a selective one of a rank-wide access mode, in which the first rank of memory and the second rank of memory exchange first and second data respectively at mutually exclusive times with the memory controller, where the first and second data each occupy more than half the width of the data path, and a sub-rank access mode, in which a first subrank of the first rank of memory and a first subrank of the second rank of memory exchange third and fourth data, respectively, at mutually exclusive times with the memory controller over a first subset of the width of the data path, and in which a second subrank of the first rank of memory and second subrank of the second rank of memory exchange fifth and sixth data, respectively, at mutually exclusive times with the memory controller over a second subset of the width of the data path, the third, fourth, fifth and sixth data each occupying no more than half of the data path width, the third data associated with an independent memory command from the fifth data and the fourth data associated with an independent memory command from the sixth data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of operating memory, the memory comprising a first rank and a second rank that share a common data path with a memory controller, the common data path having a width, each of the first rank and the second rank operable to exchange respective first and second data with the memory controller in a rank-wide access mode where the first and second data each occupy more than half the data path width in association with commands received over a shared command path, the method comprising:
configuring the memory for sub-rank memory access in which a first subrank of the first rank of memory and a first subrank of the second rank of memory exchange third and fourth data, respectively, at mutually exclusive times with the memory controller over a first subset of the width of the data path, and in which a second subrank of the first rank of memory and a second subrank of the second rank of memory exchange fifth and sixth data, respectively, at mutually exclusive times with the memory controller over a second subset of the width of the data path, the third, fourth, fifth and sixth data each occupying no more than half of the width, the third data associated with an independent memory command from the fifth data and the fourth data associated with an independent memory command from the sixth data. - View Dependent Claims (17, 18, 19, 20)
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21. An apparatus, comprising:
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memory comprising a first rank and a second rank, each of the first rank and the second rank sharing a common data path for connection to a memory controller, the common data path having a width, each of the first rank and the second rank operable to exchange respective first and second data with a memory controller in a rank-wide access mode where the first and second data each occupy more than half the data path width in association with commands received over a shared command path; and
,circuitry for each rank of memory operable to direct sub-rank memory access commands within the respective rank, such that a first subrank of the first rank of memory and a first subrank of the second rank of memory exchange third and fourth data, respectively, at mutually exclusive times with the memory controller over a first subset of the width of the data path, and such that a second subrank of the first rank of memory and a second subrank of the second rank of memory exchange fifth and sixth data, respectively, at mutually exclusive times with the memory controller over a second subset of the width of the data path, the third, fourth, fifth and sixth data each occupying no more than half of the width, the third data associated with an independent memory command from the fifth data and the fourth data associated with an independent memory command from the sixth data.
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Specification