wvmarle:
Every time you write even a single bit to the EEPROM the complete cell the bit is in has to be erased before it can be written to.
How? Why?
Does the hardware disallow a write without an erase?
Or is it simply how the software (Arduino and/or GNU compiler) is set up?
Unchanged data will simply be rewritten to the same location.
Because that's how the software is set up, right?
Also by default all bits are set. Reading a never used byte from EEPROM always returns 255.
I figured as much.