Plus42 is an advanced scientific programmable calculator that builds on the foundation of Free42, a re-implementation of the iconic HP-42S calculator from Hewlett-Packard (1988–1995). Developed by Thomas Okken, Plus42 enhances the HP-42S experience with modern features while preserving the simplicity and power of Reverse Polish Notation (RPN) programming. Available on multiple platforms, including iOS, Android, Windows, MacOS, and Linux, it caters to engineers, students, and calculator enthusiasts.
Key Features of Plus42
Enhanced Functionality
Plus42 extends Free42 by incorporating algebraic expressions inspired by the HP-27S and HP-17B/19B, unit conversions modeled after the HP-48/49/50 series, and directories for organized storage of programs and variables. It also introduces time value of money calculations, amortization schedules, and two-dimensional function plotting with zoom and pan capabilities, making it a versatile tool for complex computations.
Large, Customizable Display
Unlike the HP-42S’s limited display, Plus42 offers a default 8-row, 22-column screen (131×64 pixels) that users can resize. This larger display enhances visibility and usability, especially for viewing equations and plots, making it ideal for both desktop and mobile use.
Cross-Platform Availability
Plus42 is accessible on a wide range of devices. The iOS and Android versions are paid apps, reflecting their premium features, while Windows, MacOS, and Linux versions are free, supported by optional donations via PayPal. This flexibility ensures users can access Plus42 on their preferred platform.
RPN and Programmability
Retaining the HP-42S’s RPN system, Plus42 allows keystroke programming that is intuitive for those familiar with HP calculators. It adds advanced programming features like local variables (LSTO), a large RTN stack for recursive functions, and string/list functions, blending simplicity with modern capabilities.
Why Choose Plus42?
Plus42 stands out for its balance of nostalgia and innovation. Users praise its rock-solid performance, with some calling it the “best handheld calculator ever.” Its $10 price on mobile platforms is a bargain compared to the $100 HP-42S in 1988. The app’s 5.0-star rating on Google Play, based on 149 reviews, reflects its reliability and user satisfaction. For those needing a portable, powerful calculator, Plus42 outperforms alternatives like Droid 48, especially with features like the TVM solver.
Conclusion
Plus42 is a remarkable evolution of the HP-42S, blending classic RPN functionality with modern enhancements. Its cross-platform availability, customizable display, and advanced features make it an essential tool for professionals and enthusiasts. Whether you’re solving equations or plotting functions, Plus42 delivers unmatched performance and value.
You can download Plus42 from https://thomasokken.com/plus42/.