It 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.
When loading a skin in the skin browser, it now forces an un-cached load, so skin fixes can actually be loaded by users without delay, and without having to resort to side-loading.
Changed default landscape skin, from desktop/42ct to android/SGS-L. The old skin had keys below the display that didn't line up with the menus; you really have to have Σ+ 1/x √x LOG LN XEQ below the display for a consistent user interface.
Supports installation on external storage.