Memory module with data buffering
DC CAFCFirst Claim
1. A memory module operable in a computer system to communicate data with a memory controller of the computer system at a specified data rate via a N-bit wide data bus in response to memory commands received from the memory controller, the memory commands including a first memory command and a subsequent second memory command, the first memory command to cause the memory module to receive or output a first burst of N-bit wide data signals and a first burst of data strobes and the second memory command to cause the memory module to receive or output a second burst of N-bit wide data signals and a second burst of data strobes, the memory module comprising:
- a printed circuit board having a plurality of edge connections configured to be electrically coupled to a corresponding plurality of contacts of a module slot of the computer system;
a plurality of memory integrated circuits mounted on the printed circuit board and arranged in a plurality of N-bit wide ranks, wherein the plurality of N-bit wide ranks include a first rank configured to receive or output the first burst of N-bit wide data signals and the first burst of data strobes at the specified data rate in response to the first memory command, and a second rank configured to receive or output the second burst of N-bit wide data signals and the second burst of data strobes at the specified data rate in response to the second memory command;
circuitry coupled between the plurality of N-bit wide ranks and the N-bit wide data bus; and
logic coupled to the circuitry and configured to respond to the first memory command by providing first control signals to the circuitry and to subsequently respond to the second memory command by providing second control signals to the circuitry, wherein the circuitry is configured to enable data transfers through the circuitry in response to the first control signals and subsequently in response to the second control signals, wherein respective N-bit wide data signals of the first burst of N-bit wide data signals and respective data strobes of the first burst of data strobes are transferred at the specified data rate between the first rank and the N-bit wide data bus through the circuitry, and wherein respective N-bit wide data signals of the second burst of N-bit wide data signals and respective data strobes of the second burst of data strobes are transferred at the specified data rate between the second rank and the N-bit wide data bus through the circuitry;
wherein the data transfers through the circuitry are registered data transfers enabled in accordance with an overall CAS latency of the memory module, and the circuitry is configured to add a predetermined amount of time delay for each registered data transfer through the circuitry so that the overall CAS latency of the memory module is greater than an actual operational CAS latency of each of the plurality of memory integrated circuits.
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Abstract
A memory module operable to communicate data with a memory controller via a data bus comprises a plurality of memory integrated circuits including first memory integrated circuits and second memory integrated circuits, a data buffer coupled between the first memory integrated circuits and the data bus, and between the second memory integrated circuits and the data bus, and logic coupled to the data buffer. The logic is configured to respond to a first memory command by providing first control signals to the data buffer to enable communication of at least one first data signal between the first memory integrated circuits and the memory controller through the data buffer, and is further configured to respond to a second memory command by providing second control signals to the data buffer to enable communication of at least one second data signal between the second memory integrated circuit and the memory controller through the data buffer.
272 Citations
33 Claims
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1. A memory module operable in a computer system to communicate data with a memory controller of the computer system at a specified data rate via a N-bit wide data bus in response to memory commands received from the memory controller, the memory commands including a first memory command and a subsequent second memory command, the first memory command to cause the memory module to receive or output a first burst of N-bit wide data signals and a first burst of data strobes and the second memory command to cause the memory module to receive or output a second burst of N-bit wide data signals and a second burst of data strobes, the memory module comprising:
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a printed circuit board having a plurality of edge connections configured to be electrically coupled to a corresponding plurality of contacts of a module slot of the computer system; a plurality of memory integrated circuits mounted on the printed circuit board and arranged in a plurality of N-bit wide ranks, wherein the plurality of N-bit wide ranks include a first rank configured to receive or output the first burst of N-bit wide data signals and the first burst of data strobes at the specified data rate in response to the first memory command, and a second rank configured to receive or output the second burst of N-bit wide data signals and the second burst of data strobes at the specified data rate in response to the second memory command; circuitry coupled between the plurality of N-bit wide ranks and the N-bit wide data bus; and logic coupled to the circuitry and configured to respond to the first memory command by providing first control signals to the circuitry and to subsequently respond to the second memory command by providing second control signals to the circuitry, wherein the circuitry is configured to enable data transfers through the circuitry in response to the first control signals and subsequently in response to the second control signals, wherein respective N-bit wide data signals of the first burst of N-bit wide data signals and respective data strobes of the first burst of data strobes are transferred at the specified data rate between the first rank and the N-bit wide data bus through the circuitry, and wherein respective N-bit wide data signals of the second burst of N-bit wide data signals and respective data strobes of the second burst of data strobes are transferred at the specified data rate between the second rank and the N-bit wide data bus through the circuitry; wherein the data transfers through the circuitry are registered data transfers enabled in accordance with an overall CAS latency of the memory module, and the circuitry is configured to add a predetermined amount of time delay for each registered data transfer through the circuitry so that the overall CAS latency of the memory module is greater than an actual operational CAS latency of each of the plurality of memory integrated circuits. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A memory module operable in a computer system to communicate data with a memory controller of the computer system via a N-bit wide memory bus in response to read or write memory commands received from the memory controller, the memory module comprising:
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a printed circuit board having a plurality of edge connections configured to be electrically coupled to a corresponding plurality of contacts of a module slot of the computer system; logic coupled to the printed circuit board and configured to receive a first set of input address and control signals associated with a first read or write memory command and to output a first set of registered address and control signals in response to the first set of input address and control signals, the first set of input address and control signals including a first plurality of input chip select signals, the first set of registered address and control signals including a first plurality of registered chip select signals corresponding to respective ones of the first plurality of input chip select signals, the first plurality of registered chip select signals including a first registered chip select signal having an active signal value and one or more other registered chip select signals each having a non-active signal value; memory devices mounted on the printed circuit board and arranged in a plurality of N-bit wide ranks, wherein the plurality of N-bit wide ranks are configured to receive respective ones of the first plurality of registered chip select signals, wherein a first N-bit wide rank in the plurality of N-bit wide ranks receiving the first registered chip select signal having the active signal value is configured to receive or output a first burst of N-bit wide data signals and a first burst of data strobes associated with the first read or write command; circuitry coupled between data and strobe signal lines in the N-bit wide memory bus and corresponding data and strobe pins of memory devices in each of the plurality of N-bit wide ranks; and wherein the logic is further configured to, in response to the first read or write memory command, output first control signals to the circuitry, and wherein the circuitry is configured to enable data transfers between the first rank and the memory bus through the circuitry in response to the first control signals so that respective N-bit wide data signals of the first burst of N-bit wide data signals and respective data strobes of the first burst of data strobes are transferred through the circuitry in accordance with an overall CAS latency of the memory module; and wherein the data transfers between the first rank and the memory bus through the circuitry are registered data transfers and the circuitry is configured to add a predetermined amount of time delay for each registered data transfer through the circuitry such that the overall CAS latency of the memory module is greater than an actual operational CAS latency of each of the memory devices. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A memory module operable in a computer system to communicate data with a memory controller of the computer system via a N-bit wide memory bus in response to read or write memory commands received from the memory controller, the memory module comprising:
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a printed circuit board having a plurality of edge connections configured to be electrically coupled to a corresponding plurality of contacts of a module slot of the computer system; logic coupled to the printed circuit board and configured to receive a set of input control and address signals associated with a read or write memory command via the memory bus and to output a set of registered control and address signals in response to the set of input control and address signals, the set of input control and address signals including a plurality of input chip select signals, the set of registered control and address signals including a plurality of registered chip select signals corresponding to respective ones of the plurality of input chip select signals, the plurality of registered chip select signals including a registered chip select signal having an active signal value and one or more other registered chip select signals each having a non-active signal value; memory devices mounted on the printed circuit board and arranged in a plurality of N-bit wide ranks, wherein the plurality of N-bit wide ranks are configured to receive respective ones of the plurality of registered chip select signals, wherein a first N-bit wide rank receiving the registered chip select signal having the active signal value is configured to receive or output a first burst of N-bit wide data signals and a first burst of data strobes associated with the read/write command; circuitry between data and data strobe signal lines in the memory bus and corresponding data and data strobe pins of the memory devices, wherein the circuitry includes logic pipelines configured to enable data transfers between the first rank and the memory bus in response to the first read or write memory command, wherein respective N-bit wide data signals of the first burst of N-bit wide data signals and respective data strobes of the first burst of data strobes are transferred between the first rank and the memory bus through the circuitry in accordance with an overall CAS latency of the memory module; and wherein the data transfers between the first rank and the memory bus are registered data transfers; and wherein the circuitry is configured to add a predetermined amount of time delay for each data transfer between the memory controller and the memory devices such that the overall CAS latency of the memory module is greater than an actual operational CAS latency of each of the memory devices. - View Dependent Claims (29, 30, 31, 32, 33)
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Specification