I introduced two important changes to MegaDrum firmware starting with the version 20110411.
1. It now auto detects the crystal's frequency.
2. Added a MaxInputs configuration option. It defaults to 18 and can be increased up to the maximum for a given MCU - 28 for Atmega32/324, 56 for Atmega644. The lower MaxInputs the more Configs/Drum maps you can save in EEPROM and vice versa.
A caution: don't load a Config/Drum maps which was saved with MaxInputs value different from the current MaxInputs value.
With these two changes I will now need to include only one firmware file for each MCU variant - Atmega32, Atmega324, Atmega644.