Timer1 and External Interrupts on Arduino & HD44780 LCD Arduino use guides

This post contains the links for Timer1 and External Interrupts on Arduino & HD44780 LCD Arduino use guides are self-written and therefore, might contain several errors. Please let me know if any is spotted and I could make the ammendments

Here are some screenshots of the use guides that can be downloaded from the links below.

HD44780 LCD Arduino UG
Timer1 and External Interrupts on Arduino UG