Method and apparatus for initializing dynamic random access memory (DRAM) devices by levelizing a read domain
First Claim
1. A method for initializing a plurality of dynamic random access memory (DRAM) devices coupled to at least one memory controller, the method comprising the step of levelizing a read domain of at least one of the plurality of DRAM devices, wherein the step of levelizing comprises configuring each of the plurality of DRAM devices to respond to read commands from the at least one memory controller within a same number of clock cycles, wherein the plurality of DRAM devices do not each operate at the same speed.
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Abstract
A method and apparatus for initializing dynamic random access memory (DRAM) devices is provided wherein a channel is levelized by determining the response time of each of a number of DRAM devices coupled to a bus. Determining the response time for a DRAM device comprises writing logic ones to a memory location of the DRAM device using the bus. Subsequently, a read command is issued over the bus, wherein the read command is addressed to the newly-written memory location of the DRAM device. The memory controller then measures the elapsed time between the issuance of the read command and the receipt of the logic ones from the DRAM device, and this elapsed time is the response time of the DRAM device. Following the determination of a response time for each DRAM device, and using the longest response time, a delay is computed for each of the DRAM devices coupled to the bus so that the response time, in clock cycles, of each of the DRAM devices coupled to the bus equals the longest response time. A delay is programmed in at least one register of each of the DRAM devices coupled to the bus by writing values to at least one register of each of the DRAM devices.
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24 Claims
- 1. A method for initializing a plurality of dynamic random access memory (DRAM) devices coupled to at least one memory controller, the method comprising the step of levelizing a read domain of at least one of the plurality of DRAM devices, wherein the step of levelizing comprises configuring each of the plurality of DRAM devices to respond to read commands from the at least one memory controller within a same number of clock cycles, wherein the plurality of DRAM devices do not each operate at the same speed.
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13. An apparatus for initializing a plurality of dynamic random access memory (DRAM) devices comprising:
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at least one bus coupled among the plurality of DRAM devices and at least one memory controller; at least one levelizing circuit configured to levelize a read domain of at least one of the plurality of DRAM devices, wherein levelizing comprises configuring each of the plurality of DRAM devices to respond to read commands from the at least one memory controller in the same amount of time. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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- 20. A computer readable medium containing executable instructions which, when executed in a processing system, causes the system to perform the steps for initializing a plurality of dynamic random access memory (DRAM) devices comprising levelizing a read domain of at least one of the plurality of DRAM devices, wherein the step of levelizing comprises configuring each of the plurality of DRAM devices to respond to read commands from the at least one memory controller within a same number of clock cycles, wherein the plurality of DRAM devices do not each operate at the same speed.
Specification