Free42 is a re-implementation of the HP-42S calculator and the HP-82240 printer.

This is a complete rewrite, not using any HP code, and it does not require an HP-42S ROM image. Free42 is an Open Source project. 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. Different skins are also available.

Note: While the software is classified as free, it is actually donationware. Please consider making a donation to help support development.