Each Node chip has DDR4 memory attached. The main purpose is to store network parameter and neuron data. The maximum memory capacity of each node is 16GB. ECC feature is provided which ensures server level data integrity for the system. The DDR4 memory is organized as 4 independent channels which can operate at 2667Mbps peak rate.
DDR4接口仿真的设计主要因素包含了下图表内所示各注意事项，以及对Vref需验证电压范围，对于控制器和DDR时序的不确定性在读写两端需验证眼图。 此图版权归Mentor所有. 由于PCB设计中DDR接口的仿真、建模的复杂性，PCB的DDR接口设计越来越被广大设计师重视。 With the introduction of Per DRAM Addressability (PDA) in DDR4 memory and the internal VREF combined, discussed in this paper is a novel approach to determine the best VREF settings for a given ... JEDEC DDR4 SDRAM adopted the internal Data (DQ) reference voltage (VREFDQ) generation scheme as opposed to DDR3 SDRAM where VREF was generated by an external Per-DRAM VREF training has been also performed using PDA to study tradeoff between timing margin and total training time.
A method is provided for performing memory operations in response to instructions to perform a double data rate (DDR) memory reference voltage training in the voltage domain by a processing device and determining a DDR memory reference voltage and a DDR memory delay time based upon the memory operation. DDR4 is a step up in speed and a step down in voltage compared to its predecessor, so it is much more susceptible to interference from test pad stubs. Functional test might be expected to pick up the slack, except for constraints imposed by the Intel Memory Reference Code (MRC).