hi, my Arduino software has 2 interrupts, timer2 and USART interrupts. i compiled the executables and looked at the .elf and .hex file (the .elf files are easier to read) compiled.
i found the instructions that are to be executed if timer2 (_vector_9) or USART rx interrupt (_vector_18) kicks in. however, i also found timer0 (_vector_16) interrupt inside the compiled file. in my .pde file, i did not write anything remotely related to timer0, whereas for the other 2 interrupts, i had to write the respective ISR(). in other arduino applications, the timer0 interrupt can also be found, and only the timer0 interrupt seems to be the exception.
is the timer0 interrupt essential to every arduino app? what is its purpose? couldn't dig anything useful from the ATMega328 datasheet.