xrpn

https://github.com/isene/XRPN

A full programming language and environment extending the features of the venerable HP calculator programmable calculators. With XRPN you can accomplish a wide range of modern programming tasks as well as running existing HP-41 FOCAL programs directly. XRPN gives modern life to tens of thousands of old HP calculator programs and opens the possibilities to many, many more. New in 2.7: Complete HP-41 RAW import/export with 100% decode success - convert HP-41 programs to XRPN and back with full support for 165+ opcodes including ALL math functions (SIN, COS, LOG, etc.), flow control, and numbers.