Nonpareil RPN HP-41 Calculator Build

The early HP Reverse Polish Notation calculators have a special place in the hearts of engineers and tinkerers as there are lots of projects involving them. They haven’t been produced in decades, but [Chris Chung] has used some open source code to create DIY hardware version of the HP-41 Reverse Polish Notation (RPN) calculator.

The open source code behind the calculator is the Nonpareil High-Fidelity Calculator Simulator, and [Chris] has used it along with a custom designed readout and PCBs to create a working prototype. The simulator uses the original byte code of the HP-41 so the its behavior is exactly the same as the original calculator.

[Chris] has designed the PCBs so that the buttons and the screen are separate and join together. This neat idea means that he can try out different screens or different button PCBs and mix-and-match to find the combination that works best. He’s also designed a 3D printed case for the calculator. He does prefer using the bare buttons on the board to the 3D printed ones he printed for use with the case.

We love calculators here so there have been a bunch of articles over the years. Check out the documentation that comes along with this open source calculator, or check out this pocket calculator that emulates two other pocket calculators!

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The Connected Calculator with ESP8266

Calculator hacks have been around for a while now and we have seen the most action around the Texas Instruments TI-83 and TI-84. When [johnkimdinh] found a way to add an ESP8266 to a scientific calculator (machine translation) and this time around it’s a Kenko FX-82M calculator which appears eerily similar to the Casio FX-82M.

In his video, [johnkimdinh] demonstrates his hack which has a web interface for transmitting numbers to the calculator. This is accomplished by accessing the keypad using the ESP8266 GPIOs and it is essentially the equivalent of typing remotely. The rest of the circuit remains intact so bit more work and the other functions should be available remotely as well.

Perhaps this hack is best suited as a dedicated display for outputting measurements and other data which requires some type of post-processing to be human readable. If the next iteration delivers the ability to read from the display we’ll really be getting somewhere. We envision such calculators being used as the future of education where the connectivity is used to retrieve an array of real time parameters for assignments. Add a few sensors into the mix and it could be the next big thing for STEM.

In the past, we have had calculators brought to life to do vector and matrix math and ESP8266s connected to TI-84 calculators. After all, everyone has calculators, they simply must be hacked!

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Crippled Calculator Features Unlocked with Automated Help

[Aguilera Dario] likes his Casio fx-82ES calculator. However, it was missing a few functions, including complex numbers. A Casio fx-991ES has more functions but, of course, costs more. A quick Google revealed that if you press the right buttons, though, you can transform an fx-82ES into an fx-991ES.

Because it is apparently a buffer overflow exploit, the hack involves a lot of keys and once you cycle the power you have to do it again. [Aguilera] realized this would be a good candidate for automation and added a microcontroller to push his buttons. You can see a video of a breadboard version below. He also has a PCB version in the works that should be better integrated.

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