Entering the 2000s, 8-bit microcontrollers were the architecture of choice. In 1997, over 2 billion of the devices had been sold and, by 2006, it had reached 4 billion. However, by decade's end, 16-bit machines were overtaking 8-bit sales quantities, and Arm had more or less secured the path to 32-bit controllers. We also saw microcontrollers made accessible to the masses and a resurgence in home-brew audio projects thanks to MP3.