Just see what works. What board do you have? Most people seem to use a Nano or a Uno - in which case the processor is an ATMEGA328P - could be normal or old bootloader - just try both if it's not working.
Just see what works. What board do you have? Most people seem to use a Nano or a Uno - in which case the processor is an ATMEGA328P - could be normal or old bootloader - just try both if it's not working.