If you have thirty minutes, you can see just how easy it is to duplicate his feat. The blue pill board has to be programmed once using an STM32 programmer. After that, you can use most standard Forth words and also use some that can manipulate the low-level microcontroller resources.
The blue pill boards are really quite amazing for the price, offering a lot of computing power for a few bucks. Adding an interactive high-level language to it makes it even more usable. We have covered the platform several times using the Arduino IDE and Platform.io.
We’ve done our own take on this same topic. Mecrisp is available for quite a few other platforms and we’ve covered quite a few of them. If you want to know more about Forth as a language, [Elliot Williams] covered that earlier this year.