Free42 Decimal

About

Free42 Decimal is a re-implementation of the HP-42S Scientific Programmable Calculator and HP-82240 Printer, written from scratch without any HP code and without requiring an HP-42S ROM image. Although it adds enhancements beyond the original calculator, it remains fully compatible with the HP-42S in both its user interface and its ability to run programs written for the HP-42S. The project is open source, released under the GNU General Public License, version 2.

Free42 is available on several platforms, including macOS 10.15 (Catalina) or later, as well as Windows, Linux, Android, and iOS. The site's documentation covers its extended functionality, such as program import and export, time and date functions, configurable word size for BASE functions, enhanced debugging, local variables, and access to accelerometer, GPS, and compass data on Android and iOS devices. For general use, the original HP-42S Owner's Manual is recommended, along with an alternative manual by José Lauro Strapasson and Russ Jones.

The website also describes Plus42, an enhanced version of Free42 with a larger display, algebraic expressions, attached units, directories, TVM, and 2D function plotting. Users who find Free42 useful can support the project through donations processed by PayPal.