This Open Source WP 34S calculator is based on a HP-42S RPN Scientific Calculator

This Open Source WP 34S calculator is based on a HP-42S RPN Scientific Calculator

It uses the mechanics and hardware of an HP-20b Business Consultant or an HP-30b Business Professional, respectively, so you benefit from the excellent processor speed of these pocket calculators (this software, using these two base calculators, turns either of these calculators into a powerful keystroke programmable scientific device - or you can just run the emulator software). And with an HP-30b you also get the famous rotate-and-click keys, giving you the tactile feedback that has been appreciated in vintage Hewlett-Packard calculators for decades.

The function set of this WP 34S is based on the famous HP-42S RPN Scientific of 1988, the most powerful programmable RPN calculator industrially built so far. They have expanded the set, incorporating the functions of the renowned computer scientist’s HP-16C, the fraction mode of the HP-32SII, and probability distributions similar to those of the HP-21S. They have also included numerous additional useful functions for mathematics, statistics, physics, engineering, programming, I/O, etc., such as:

+ Euler’s Beta and Riemann’s Zeta functions, Bernoulli and Fibonacci numbers,
Lambert’s W, the error function, and the Chebyshev, Hermite, Laguerre, and
Legendre orthogonal polynomials (no more need to carry heavy printed tables),
+ many statistical distributions and their inverses: Poisson, Binomial, Geometric,
Cauchy-Lorentz, Exponential, Logistic, Weibull, Lognormal, and Gaussian,
+ programmable sums and products, first and second derivatives, solving quadratic equations for real and complex roots,
+ testing for primality,
+ integer computing in fifteen bases from binary to hexadecimal,
+ extended date and time operations and a stopwatch3 based on a real-time clock,
+ financial operations such as mean rate of return and margin calculations,
+ 88 conversions, mainly from old Imperial to universal SI units and vice versa,
+ 50 fundamental physical constants as accurate as used today by national standards
institutes such as NIST or PTB, plus a selection of important constants from
mathematics, astronomy, and surveying,
+ bidirectional serial communication with your computer, as well as printing on an HP
82240A/B 4,
+ battery-fail-safe on-board backup memory,
+ Greek and extended Latin letters covering the languages of almost half of the world’s population (upper and lower case in two font sizes), plus mathematical symbols.

The WP 34S is the first RPN calculator overcoming the limits of a four-level stack. The WP 34S features a choice of two stack sizes expanded by a complex LASTx register: traditional four stack levels for HP compatibility, eight levels for convenient calculations in complex domain, for advanced real calculus, vector algebra in 4D, or whatever application you have in mind. You will find a full
set of commands for stack handling and navigation in either stack size.

Furthermore, the WP 34S features up to 107 global general purpose registers, 112 global user flags, up to 928 program steps in RAM, up to 6014 program steps in flash memory, a 30 byte alpha register for message generation, 16 local flags as well as up to 144 local registers allowing for recursive programming, and 4 user-programmable hotkeys for your personal favorite functions.

The WP 34S is named in honour of the HP-34C from 1979, one of the most powerful compact LED pocket calculators.

They also include a detailed 211 owners manual. You can grab a download or have a look at the source code at The emulator software for Linux, Mac and Windows can be found at or you can buy ready made ones from

#WP34S #HP42S #HP30b #HP20b #HPcalculator

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