Here is an extra credit mini-project that you may like to try. It gives you some appreciation for how hard your Arduino works to make things look easy and make you, as an Arduino developer, look good.
Caution Improper use of the commands used in these exercises can render your Arduino inoperable. If you accidentally overwrite the Arduino bootloader (a distinct possibility), you need a dedicated device programmer, such as an Atmel STK500, ARVISP mkII, AVR Dragon, or other, working Arduino to replace it.
You need a plain-text editor or programmer’s editor. The editor in the Arduino software thinks you’re writing an Arduino sketch ...