28.2.1.5 Row Contents

Each physical FLASH row initially stores the contents of two logical EEPROM memory pages. This halves the available storage space for the emulated EEPROM but reduces the overall number of row erases that are required, by reserving two pages within each row for updated versions of the logical page contents. See Figure 28-3 for a visual layout of the EEPROM Emulator physical memory.

As logical pages within a physical row are updated, the new data is filled into the remaining unused pages in the row. Once the entire row is full, a new write request will copy the logical page not being written to in the current row to the spare row with the new (updated) logical page data, before the old row is erased.

This system allows for the same logical page to be updated up to three times into physical memory before a row erasure procedure is needed. In the case of multiple versions of the same logical EEPROM page being stored in the same physical row, the right-most (highest physical FLASH memory page address) version is considered to be the most current.