The TetraHub does not support EEPROM sizes larger than 4K. The 4K EEPROM 25LC040 was used initially because it was the smallest SPI EEPROM we could find at the time. But ST-Micro and Atmel sell 2K and 1K. Fairchild (and maybe Xicor) also sell 2K. From the look of the datasheet of some of these parts HX2 will work with the 1K and 2K devices, which would waste less memory, and maybe save a few cents. But we have NOT tested and confirmed these parts. The SPI EEPROM used (and recommended) in the reference design is MICROCHIP 25LC040. TetraHub can interface with the '010s and '020s and '040s due to the read command format being the same. It cannot interface with 8K EEPROM 25LC080.