How Serial Resistors in Matrix Keypads Help Increase Your Security. Have you ever wondered what those buttons do inside your computer's keyboard? They are what allow the keyboard to send the letter "A" to your computer when you press the button labeled "A." But there are so many keys! What are they all doing? It turns out that keyboards use a pretty old technology to transfer data called resistors. These components look like little black stripes and come in different values. They're like tiny electronic traffic cops, telling the other components how...