While working on the next release of PixelMaestro, I came across a problem of storing long-term data on an Arduino. I have a system in place where configuration changes are sent to an Arduino over USB as byte arrays, and as the Arduino reads the array it applies the changes. The problem is those changes disappear as soon as you restart the device. How, then, does one store persistent data without having to add an SD card or extra memory? Enter EEPROM.