<li>74HC165 shift register chips
</ul>

<h4>GPIO port inputs</h4>
<p>
   One way to connect a button is to wire it directly to a Pico GPIO port.
   That's the easiest setup, but it limits you to a relatively small number
   of buttons, given the relative small number of Pico GPIO pins.
</p>
<p>
   To connect a button to a GPIO port, connect one of the button's switch
   terminals to the GPIO pin, and connect the other switch terminal to
   a Pico GND pin.
</p>
<p>
   The Pico GND pins all connect to the com