May 18, 2026
Calculator chaos, but make it wholesome
Designing an FPGA Calculator from Scratch
He built a calculator from the ground up, and commenters are equal parts impressed and jealous
TLDR: A maker built a scientific calculator from scratch, including its tiny internal brain, to get exact decimal math and total control over how it works. Commenters loved the deep dive, with the biggest mood being admiration mixed with envy from people wishing they had a reason to build something this gloriously over-the-top.
A hobby project about building a calculator from absolute scratch somehow turned into catnip for the “show me how it really works” crowd. The maker isn’t just assembling a gadget — he’s creating the whole tiny brain behind it, step by step, from the number system to the keys, screen, battery, and even the custom software that makes the thing answer correctly. In plain English: this is someone deciding a normal calculator is too boring, then building a whole one from the inside out so it can do math the “right” way, with exact decimal digits and no weird rounding surprises.
And in the comments? The reaction is basically “this rules” mixed with “wow, I wish I had an excuse to do this.” One early fan called it a “great project walkthrough,” praising the full journey from raw logic to real math functions like sine and multiplication. That set the tone: admiration, curiosity, and a little bit of worship for anyone patient enough to turn tiny electronic switches into a working scientific calculator. The closest thing to drama is the relatable envy. One commenter practically sighed through the screen, saying they’d love to have a “real application” for a field-programmable chip — aka a reprogrammable hardware board — someday. Translation: this project is so cool it made onlookers jealous of not having their own ridiculous hardware quest. No flame war, just the gentlest possible nerd meltdown: awe, longing, and a lot of “okay, fine, now I want one too.”
Key Points
- •The article describes a scientific calculator that uses binary-coded decimal arithmetic, storing each decimal digit as a 4-bit nibble for exact decimal behavior.
- •The calculator is paired with a custom nibble-oriented CPU designed specifically to support BCD-based computation.
- •The hardware implementation targets an Altera Cyclone II FPGA and uses Quartus, Verilator, ModelSim, Qt, and WebAssembly in its toolchain and prototype workflow.
- •The ten-chapter series covers numerical algorithms, a 12-bit instruction set, a Python two-pass assembler, microcode, scripting for key functions, and final hardware assembly.
- •The project reports that verified algorithms ultimately run on the custom processor with results correct to 14 decimal digits.