The Joo Programming Language

I once did a serial console calculator just for fun.

char* sStack[ ] = {
  "DIV","MUL","ADD","SUB","Y^X","LOG","NLG","10X","1/X","e^X",
  "SQR","X^2","SIN","COS","TAN","ASN","ACS","ATN","DEG","RAD",
  "DEC", "RTT","DPR"};

https://forum.arduino.cc/t/dont-cross-the-streams-fp-scientific-calculator-serial-co-processor/144054/12

... an eternity ago.