Free42

Thomas Okken

About this app

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.

Ratings and reviews

I still have two HP42s, one for my office at work, one for my office at home, both in a drawer. Free42 now resides on my phone and computers. It is a perfect emulation with some significant advantages in stack height and memory. I occasionally miss the HP's programmability, but usually just turn to a spread sheet for highly repetitive calculations or more specialized apps or programs for more challenging work.

For a calculator app that optimizes keystrokes, this is the one. For the classic HP calculator experience in an app, start here. If you want an RPN calculator, you won't find a consistent, faster, smaller, scientific, featured calculator cheaper. If you want graphing or algebraic or textbook entry, keep looking.

Oops! My apologies! I mixed up two different HP emulators. and I was awfully cranky about it. My apologies. Free42 appears to be a pretty good HP calculator emulator, I was just upset because it doesn't look like my favorite, which doesn't work any more. Free42 seems to work just fine. I know there are what, a couple of dozen skins available, too.

What's new

Fixed handling of invalid number keys in BINM and OCTM modes.