Description
The U631H256has two separate modes of operation: SRAM mode and nonvolatile mode. In SRAM mode, the memory operates as an ordinary static RAM. In nonvolatile operation,  data  is transferred  in parallelfromSRAM to EEPROM or from EEPROM to SRAM. In this modeSRAMfunctions are disabled.

FEATUREs
High-performance CMOS nonvolatile static RAM 32768 x 8 bits
25, 35 and 45 ns Access Times
10, 15 and 20 ns Output Enable Access Times
Software STORE Initiation
Automatic STORE Timing
10⁵ STORE cycles to EEPROM
10 years data retention in EEPROM
Automatic RECALL on Power Up
Software RECALL Initiation
UnlimitedRECALL cycles from EEPROM
Unlimited Read and Write to SRAM
Single5 V ± 10% Operation
Operating temperature range
               0 to 70 °C
              -40 to 85 °C
CECC 90000 Quality Standard
ESD characterization according MIL STD 883C M3015.7-HBM(classification see IC Code Num bers)
Packages: PDIP28 (300 mil)
             PDIP28 (600 mil)
             SOP28 (330 mil)