Free42!

Free42 is a re-implementation of the HP-42S calculator and the HP-82240 printer. It is a complete rewrite, not using any HP code, and it does not require an HP-42S ROM image. The executables and source code are released under the terms of the GNU General Public License, version 2.All third-party code used in Free42 is either in the public domain, or licensed under terms compatible with GPLv2, or used with the authors permission.