Board.txt edition on Mac OS X

Hello there,

I'm in the process of trying 20MHz with the AtMega328P. Every tutorial start with the modification of the board.txt file which I correctly found on my mac under the arduino package Arduino/Contents/Java/hardware/arduino/avr/boards.txt

My problem is that my modification doesn't appears at all in the IDE. I even tried to delete the file and the IDE still show me all the boards... I should do something bad obviously.

I expect there is some other hidden places that stores boards information but I cannot manage to find it.

Any help is welcome.


Now with board manager, the board packages are stored elsewhere. I don't know where it is on mac, only windows.

If you just need support for 20mhz ATMega 328p, might I recommend this core? It supports 20mhz out of the box, can be installed and updated through board manger, works with all the atmega x8 series (ie, 8, 48, 88, 168 and 328 p and non-p) and is being actively and competently maintained: GitHub - MCUdude/MiniCore: Arduino hardware package for ATmega8, ATmega48, ATmega88, ATmega168, ATmega328 and ATmega328PB

If you've updated your Arduino AVR Boards version then it's located at:
I second using MiniCore but it can be educational to open up boards.txt and have a look.