A closer look at Raspberry Pi RP2040 Programmable IOs (PIO)
amazing! pio is like the third CPU. That can excute assemble instruntions. Although ,it only has 9 instruntions.
https://www.cnx-software.com/2021/01/27/a-closer-look-at-raspberry-pi-rp2040-programmable-ios-pio/amp/