Juan Ramón is 15 years old, lives in Almería, and is working on a project with an unusually ambitious goal: to build an open-source operating system for scientific and graphing calculators that could help reduce their cost to a fraction of today’s commercial models.
The project is called NumOS and is part of NeoCalculator, an open-source calculator initiative built around affordable embedded hardware. Its public message is direct: break the dependence on expensive closed devices by creating a calculator platform that can be studied, modified, repaired and improved by anyone.
The idea is not simply to make a cheaper calculator. It is to rethink the calculator as an educational computing device: open hardware, open software, a transparent mathematical engine and a user interface designed for modern students rather than locked-down ecosystems. According to the project’s own materials, the target is a calculator-class device around the 15 euro or dollar hardware range, compared with commercial graphing calculators that often sit well above 100 euros.
That figure should be read carefully. A hardware cost target is not the same as a final retail price. Manufacturing, certification, casing, distribution, warranty, packaging and support all add cost. But even with that caveat, the project raises an important question: why are many advanced calculators still so expensive when low-cost embedded hardware is now powerful enough to run sophisticated interfaces and mathematical tools?
A calculator built on open hardware principles
At the centre of NeoCalculator is the ESP32-S3, a low-cost microcontroller from Espressif with dual-core processing, enough memory for embedded graphical applications and broad developer support. The project documentation describes a configuration based on an ESP32-S3 N16R8, with 16 MB of flash memory and 8 MB of PSRAM, paired with a 320 × 240 IPS display using the ILI9341 controller.
That may sound modest compared with a smartphone or laptop, but for a dedicated calculator it is a serious platform if the software is carefully designed. NumOS is written in C++17 and uses LVGL 9.x, a popular embedded graphics library, to deliver a fluid graphical interface. The project’s website claims a 60 FPS interface target, powered by hardware SPI and LVGL.
The proposed software environment includes a launcher-style interface and applications for calculations, equations, sequences, graphing, regression, statistics, tables, probability, Python and settings. The documentation also refers to a broader roadmap that includes symbolic mathematics, scripting, WiFi features, OTA updates and more advanced mathematical capabilities.
| Component | Project details |
|---|---|
| Project name | NumOS / NeoCalculator |
| Developer | Juan Ramón, 15, from Almería |
| Hardware target | ESP32-S3-based calculator |
| Main language | C++17 |
| Graphics stack | LVGL 9.x |
| Display | ILI9341 IPS, 320 × 240 |
| Memory configuration | 16 MB flash, 8 MB PSRAM |
| Mathematical backend | Giac C++ integration referenced in project documentation |
| Licensing approach | Open-source software and hardware-oriented design |
| Cost ambition | Around 15 euros/dollars in hardware target |
One of the most interesting technical claims is the use of a compact CAS, or computer algebra system, designed to support symbolic mathematics under tight memory constraints. The project’s site refers to a CAS engine fitting within 97 KB of SRAM, while repository documentation points to an integration with Giac C++ as the canonical symbolic backend. Giac is a known computer algebra system used in educational and mathematical tools, so its presence would give the project a stronger mathematical foundation than a purely custom symbolic engine written from scratch.
The project also states that the hardware and software are intended to be open, with future OSHWA certification mentioned as an objective. That detail matters: until certification is actually granted, it should be described as an aspiration rather than a completed status.
The real challenge: not only price, but trust
NeoCalculator compares itself with devices such as the HP Prime, TI-84 Plus CE and NumWorks, all of which are established products in the educational calculator market. The project’s message is provocative: if a capable open-source calculator can be built on low-cost hardware, the traditional pricing model deserves to be questioned.
But competing with commercial calculators is harder than producing a working prototype. Schools, universities and exam boards do not choose calculators only by raw specifications. They care about reliability, battery life, exam compatibility, durability, predictable behaviour, support, documentation and long-term availability.
A calculator used in education must survive backpacks, classrooms, exam halls and years of everyday use. It must boot reliably, avoid crashes, produce correct results, support familiar workflows and comply with regulations in different education systems. That is a much higher bar than building a demo that works on a development board.
There is also the question of trust. Teachers and students need to know that graphing, statistics, algebra and numerical results are correct. In mathematical tools, a small bug can have large consequences. If NumOS wants to become more than a maker project, testing and validation will be as important as interface design.
Still, open source gives the project a powerful advantage. Anyone can inspect the code, review the algorithms, contribute fixes, adapt the system and learn from the implementation. In a closed calculator, students use the device. In an open one, they can understand it.
That educational dimension may be the strongest part of the project. A calculator like NeoCalculator could teach more than mathematics. It could teach embedded programming, graphical interfaces, memory management, hardware design, operating system structure and the relationship between software and physical devices.
A young open-source project with unusual ambition
What makes the story stand out is not just the technical roadmap. It is the fact that the project is being led by a 15-year-old developer from Almería. At an age when many students are just beginning to learn programming, Juan Ramón is documenting hardware constraints, memory issues, graphical architecture, symbolic computation and a product vision aimed at one of the most conservative categories in educational technology.
The repository material appears to document real engineering work: hardware notes, GPIO conflicts, memory configuration, boot issues, roadmap stages and application planning. That transparency is valuable. Open-source projects grow not only through code, but through the trail of decisions, mistakes and fixes that others can follow.
There are, of course, unanswered questions. It is not yet clear when a complete hardware revision will be ready for wider assembly, how the casing will be produced, what the final bill of materials will be, how battery life will perform, whether the system will remain stable under real classroom use, or how many contributors the project can attract.
The roadmap is also very ambitious. It includes features that would challenge even a small professional team: symbolic algebra, graphing, statistics, scripting, connectivity, updates and a polished user interface. The risk for any young open-source project is trying to do too much before the core experience is stable.
A realistic path would be to focus first on the essentials: fast boot, stable input, reliable numerical calculation, graphing, a clear interface, safe file storage, battery management and strong documentation. Once that foundation works, advanced CAS features, scripting and connectivity can mature without overwhelming the project.
Even if NeoCalculator never replaces commercial graphing calculators at scale, it already has value as a learning platform. It shows students that hardware is not magic, that operating systems can be built, that mathematical tools can be open and that educational devices do not have to be sealed boxes.
In that sense, NumOS is less a direct attack on calculator companies than a reminder of what open technology can do. It gives curious students a system they can assemble, inspect and improve. It turns the calculator from a purchased object into a programmable machine.
The commercial calculator market may not change overnight. Schools move slowly, certification matters and established brands have deep distribution channels. But the existence of projects like NumOS matters because it creates alternatives, pressure and imagination. It shows that a teenager with the right tools, documentation and open-source culture can challenge assumptions that have been sitting in classrooms for decades.
Juan Ramón’s project still has a long road ahead. It needs contributors, testing, hardware refinement, documentation and realistic milestones. But its core idea is strong: scientific calculators should be more affordable, more transparent and more educational than they are today.
Frequently asked questions
What is NumOS?
NumOS is an open-source operating system for a scientific and graphing calculator platform called NeoCalculator.
Who is developing it?
The project is being developed by Juan Ramón, a 15-year-old from Almería, according to the information provided about the initiative.
Is NeoCalculator already a finished commercial product?
No. It should be understood as an open-source project in development, with public documentation, hardware plans and an ambitious roadmap.
Can it really cost around 15 euros?
The project presents that figure as a hardware cost target. A final product would also need casing, manufacturing, certification, support and distribution, so the real end-user price could be higher.
Why is open source important for a calculator?
Because students, teachers and developers can inspect the code, understand how the device works, modify it, repair it and adapt it to different educational needs.