So what's the maximal number of code lines? Just an estimate. 100, 200, 500?
You can potentially put an interpreter and SD card file system code in the program memory, and connect up a 2Gbyte SD flash card to contain programs to be interpreted, but that's probably cheating, right?
I narrowed the issue down to DateTime.h, with EEPROM.h and wire.h, was too much for the 168.
I narrowed the issue down to DateTime.h