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 2.6: Comprehensive regression test framework with 58 automated tests and HP-41 RAW file viewer for inspecting thousands of legacy HP-41 programs.