I/O ports control the pins of a microcontroller and allow them to be individually configured as input pins or output pins. That’s such a broad statement, it should fit just about any newbie course or introduction to microcontroller programming. However, to truly comprehend and exploit a microcontroller’s I/O abilities, you need to delve deeper into the machine. In this article, Elektor book author Warwick Smith pulls it off by demo-ing some assembly-code programming on the popular ATtiny micro. Convincing? Let’s check it out!