Hello Weijun,
About BG0/BG1 signals, see explainations below, please!
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Bank group input: BG0-BG1 can select which bank group the current ACT, RD, WRT or PRE command operates on. In the MRS command, BG0 also participates in the selection of mode registers. In X4 and X8 systems, there are BG0 and BG1, while in x16 system, only BG0.
Bank组输入：BG0-BG1可以选择当前的ACT、RD、WRT或是PRE命令是对哪一个Bank组进行操作。在MRS命令中，BG0也参与模式寄存器的选择。在x4、x8系统中，有BG0与BG1，而x16系统中，仅有BG0。
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Have a nice day!
BR,
Weidong Sun
