Microcontrollers – what are they and what can you do with them? First developed in the late 1970’s they are single chip computers. They were developed to perform a single task like control a printer, operate a camera or control a TV set or control a car engine. One chip could do any of these tasks by writing the code and loading it into the chip. For Ham radio one of these chips could run a radio, operate an antenna tuner, measure SWR and power or do CW decoding. This is just an introduction to these controllers and what you can do with Arduino and ESP32 boards.