Found 4 alternatives for DS1321S by Rochester Electronics, LLC. Memory Controllers — 16-SOIC (0.154", 3.90mm Width).
IC SRAM NONVOLATIL CNTRL 16-SOIC
POWER SUPPLY SUPPORT CIRCUIT
IC X4 SRAM NONVOL CTRLR 16-SOIC
IC CTRLR NV W/BATT MON 5V 16SOIC