Calctro by Frog //ROi
256 bytes intro for HP-41
It is written in FOCAL and works correctly with real hardware (use calctro.prg/raw) and v41 emulator (which has a problem with sound sync though). No synthetic instructions.
If you don't have HP-41 + HP82106A, check out Youtube video: https://www.youtube.com/watch?v=fJzmQ0yoP8A
There is also extended version (calctro_extended.prg/raw) that longer but works only with v41 because it requires twice more memory.
License: MIT