Author Topic: Free42 is a replica of the HP-42S RPN scientific calculator & HP-82240 printer  (Read 241 times)

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Free42 is a FREE Open Source replica of the HP-42S RPN scientific calculator with the HP-82240 printer unit ...

For Desktop OSes (Linux - Windows - Mac OS X) ----> Go Here.

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.

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.

Requires Android
4.0 and up

Compatibility:    Requires iOS 8.0 or later. Compatible with iPhone, iPad, and iPod touch.


There is no manual for Free42 per se, but since it is an accurate simulation of the HP-42S, the original HP-42S Owner's Manual should be adequate for most purposes. I also recommend the Alternative HP-42S/Free42 Manual, written by José Lauro Strapasson and Russ Jones; you can get it there, in PDF and Word formats. Finally, the HP-42S Programming Examples and Techniques book is a great source of advanced programming advice and inspiration.

The User Interface functionality that is specific to Free42, e.g. printer emulation, skin switching, etc., is fairly simple and should be self-explanatory, but Free42 also has extended functionality in the calculator simulation: program import/export, time and date functions, configurable word size for BASE functions, enhanced debugging functions, local variables, and access to the accelerometer / GPS / compass on Android and iOS devices. These are all documented on the web site.

Loading and Saving Programs:

Loading and saving programs is possible in all Free42 versions. The exact process is pretty straightforward in the desktop versions (Windows, MacOS, Linux), but it is a bit more complicated on mobile devices.

Starting with release 2.0, you can use Copy and Paste to get programs into and out of Free42. In PRGM mode, Copy puts a text representation of the current program onto the system clipboard, and Paste takes a text representation of a program from the clipboard and loads it as the last program. This works in all Free42 versions, including mobile.

HP-42S users manual (PDF): HP-42S Users Manual


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