18.104.22.168. Command and Address Signals
For DDR3, the CS#, RAS#, CAS#, WE#, CKE, and ODT pins are SDRAM command and control pins. For DDR3 SDRAM, certain topologies such as RDIMM and LRDIMM include RESET#, PAR (1.5V LVCMOS I/O standard), and ALERT# (SSTL-15 I/O standard).
Although DDR4 operates in fundamentally the same way as other SDRAM, there are no longer dedicated pins for RAS#, CAS#, and WE#, as those are now shared with higher-order address pins. DDR4 still has CS#, CKE, ODT, and RESET# pins, similar to DDR3. DDR4 introduces some additional pins, including the ACT# (activate) pin and BG (bank group) pins. Depending on the memory format and the functions enabled, the following pins might also exist in DDR4: PAR (address command parity) pin and the ALERT# pin.
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