Forth has a long history of being a popular hacker language ... Mecrisp Forth and put it on the very inexpensive STM32 “blue pill” board to create a development system that cost about $2 ...

The brains of the operation is an STM8S103F module, aka the Blue Pill, which is paired with a DS18B20 temperature sensor. [Tim]’s original coaster has one in a TO-92 package embedded in the top ...