Life & fun · December 30, 2024
WIP NandToTetris Emulator in pure C – logic gates to ALU to CPU to PC
* OPEN TO CONTRIBUTIONS * NandToTetris is a course which has you build a full computer from: Logic gates -> Chips -> RAM -> CPU -> Computer -> Assembler -> Compiler -> OS -> Tetris All this is done via software defined hardware emulation. I'm building an emulator for this entire stack in C. How is my approach different to other projects that build emulators? - No external dependencies (so far) - Start with a single software defined NAND gate in C - EVERYTHING is built from this base chip - Don't use certain programming utilities: boolean logic operators, bitwise logic operators etc Instead…
In plain words
This is a pure C emulator project for the Nand2Tetris course that builds a complete computer system from basic logic gates upward. Starting with a single software-defined NAND gate, the project constructs everything—chips, RAM, CPU, assembler, compiler, and operating system—without external dependencies. It's designed for educators and students learning computer architecture who want to understand how digital systems work from first principles, with the unusual constraint of avoiding built-in boolean and bitwise operators to force implementation from foundational gates.
written from the facts on this page · September 2026
From the sources
In the maker’s words, at launch
* OPEN TO CONTRIBUTIONS * NandToTetris is a course which has you build a full computer from: Logic gates -> Chips -> RAM -> CPU -> Computer -> Assembler -> Compiler -> OS -> Tetris All this is done via software defined hardware emulation. I'm building an emulator for this entire stack in C. How is my approach different to other projects that build emulators? - No external dependencies (so far) - Start with a single software defined NAND gate in C - EVERYTHING is built from this base chip - Don't use certain programming utilities: boolean logic operators, bitwise logic operators etc Instead we leverage the gates/chips to implement such logic I build more and more base chips from the NAND gate - Simple gates: OR, AND, NOT, XOR (5 total "gates") - Simple chips: DMux, Mux (11 so far, "combinatorial" chips - 16 bit variants For comparison, most emulator projects start right at the CPU level and don't sequentially build primitive structures. So a lay-person, or person unfamiliar with PC architectures is missing some lower-level information. Typical emulators look at CPU truth table / Instruction set and implement that logic directly in code. More straight forward, way fewer lines of code - but you skip all the gates/chips fun. ------ Confused? Heres example code for my NAND gate: void nand_gate(Nand *nand) { nand->output.out = !(nand->input.a & nand->input.b); } From this gate I build a NOT gate (note, no boolean operators) void not_gate(Not * not ) { Nand nand = { .input.a = not ->input.in, .input.b = not ->input.in, }; nand_gate(&nand); not ->output.out = nand.output.out; } Then OR / AND / XOR / MUX / DMUX ..... and their 16 bit versions. Heres a more complex chip, a 16bit Mux-8-way chip /* * out = a if sel = 000 * b if sel = 001 * c if sel = 010 * d if sel = 011 * e if sel = 100 * f if sel = 101 * g if sel = 110 * h if sel = 111 */ void mux16_8_way_chip(Mux16_8_Way *mux16_8_way) { Mux16_4_Way mux16_4_way_chip_a, mux16_4_way_chip_b; Mux16 mux16_chip_c; // Mux a memcpy(mux16_4_way_chip_a.input.sel, mux16_8_way- >input.sel, sizeof(mux16_4_way_chip_a.input.sel)); memcpy(mux16_4_way_chip_a.input.a, mux16_8_way->input.a, sizeof(mux16_4_way_chip_a.input.a)); memcpy(mux16_4_way_chip_a.input.b, mux16_8_way->input.b, sizeof(mux16_4_way_chip_a.input.b)); memcpy(mux16_4_way_chip_a.input.c, mux16_8_way->input.c, sizeof(mux16_4_way_chip_a.input.c)); memcpy(mux16_4_way_chip_a.input.d, mux16_8_way->input.d, sizeof(mux16_4_way_chip_a.input.d)); mux16_4_way_chip(&mux16_4_way_chip_a); // Mux b memcpy(mux16_4_way_chip_b.input.sel, mux16_8_way->input.sel, sizeof(mux16_4_way_chip_b.input.sel)); memcpy(mux16_4_way_chip_b.input.a, mux16_8_way->input.e, sizeof(mux16_4_way_chip_b.input.a)); memcpy(mux16_4_way_chip_b.input.b, mux16_8_way->input.f, sizeof(mux16_4_way_chip_b.input.b)); memcpy(mux16_4_way_chip_b.input.c, mux16_8_way->input.g, sizeof(mux16_4_way_chip_b.input.c)); memcpy(mux16_4_way_chip_b.input.d, mux16_8_way->input.h, sizeof(mux16_4_way_chip_b.input.d)); mux16_4_way_chip(&mux16_4_way_chip_b); // Mux c mux16_chip_c.input.sel = mux16_8_way->input.sel[2]; memcpy(mux16_chip_c.input.a, mux16_4_way_chip_a.output.out, sizeof(mux16_chip_c.input.a)); memcpy(mux16_chip_c.input.b, mux16_4_way_chip_b.output.out, sizeof(mux16_chip_c.input.b)); mux16_chip(&mux16_chip_c); memcpy(mux16_8_way->output.out, mux16_chip_c.output.out, sizeof(mux16_8_way->output.out)); } ----- Progress: I have only started this project yesterday, so have completed 1 out of 7 hardware projects so far
Does the same job
all alternatives →- IMI made a programmable computer from NAND gates2024 · github.com · ▲420
I am proud to present my solo hobby project NAND. This year-long undertaking follows the completed Nand to Tetris course, but ported to the web with its own runtime, user interface, and IDE. Using the "Load example program" selector, you can try out some programs I wrote on NAND's emulated hardware such as 2048, a genetic algorithm, and a manual stack overflow to corrupt the screen. Check out NAND at https://nand.arhan.sh Additionally, I've authored an extensive writeup about the project. Read about it on the GitHub repository's readme.
- IWI wrote my own RTS game engine in C2021 · github.com · ▲1,102
- WBWe built an 8-bit CPU as 2nd year EE studentsJun 2026 · github.com · ▲108
Hi! me and my friends together built an 8 bit CPU implemented in Logisim purely from scratch. The control unit of this system does not implement the generic microcode ROM or any kind of RAM. This was made purely from discrete logic gates and coded the system to run different programs. key features: Custom 16-instruction Harvard ISA, 8-bit fixed format, 4 general purpose registers Hardwired control unit built entirely from AND/OR gate logic matrix Dual-phase clocking to eliminate race conditions Bootstrap Control Unit that cold-boots via ROM-to-RAM transfer Early-exit conditional…
- ANA nibble-oriented CPU in Verilog to build a scientific calculatorMay 2026 · github.com · ▲119
The core question: how did HP's scientific calculators actually work at the gate level? That rabbit hole led to building one from scratch. The architectural decision everything else follows from: a decimal calculator should store numbers as BCD — one decimal digit per 4-bit nibble. A standard byte-oriented CPU (Z80, 6502) fights that layout constantly. So I designed a small custom CPU in Verilog where 4 bits is the natural data width and memory is nibble addressable. What the project covers: - Custom CPU: Harvard architecture, 12-bit ISA, 8-state execution FSM, hardware stack guard with a…
- H1Homebrew 16bit CPU from 74HC logic with C compiler and Unix-like OS2023 · sol-1.org · ▲192
This is a 16bit CPU+Minicomputer from pure 74 series logic. It has user/kernel modes, virtual memory, prioritized IRQ's and DMA. It has a full C compiler and a unix-like OS. It's still in development.
- IMI made a game where you build a CPU from logic gatesJul 2026 · select.supply · ▲102
I built ChipBuilder to make computer architecture more approachable through interactive puzzles. You start with basic logic gates like AND, OR, and NOT, then gradually combine them into adders, multiplexers, memory, an ALU, and eventually a complete CPU. Once you've built the hardware, you can write assembly programs that run on the processor you created. The game is inspired by courses like Nand2Tetris, but everything runs directly in the browser with a visual circuit editor, simulations, and progressively harder challenges.
More life & fun this month
the category →- TL
Life & fun · 10d ago · louisabraham.github.io
Photosynthesis fires two of your iPhone
Life & fun · 29d ago · photosynthesis.camera
SoloUno▲310Take control of hair pulling, nail biting & skin picking
Life & fun · 28d ago · solouno.io
Scroll through all 43,252,003,274,489,856,000 reachable Rubik's Cube permutations.
Life & fun · 27d ago · everycube.alen.is
Hi HN, I built Eigendrum, a web tool that solves the 2D wave equation for arbitrary shapes so you can hear what they sound like as drums. How it works: * Solves -∇²u = λu using finite element analysis (Kφ = λMφ) on a triangle mesh. * Validated to <0.1% error against closed-form solutions for circles (Bessel zeros) and rectangles. * Sound model factors in strike location, Rayleigh damping, and mallet width. * Includes Kac drums I & II to demonstrate identical sound spectra from different geometries. * No frameworks, build steps, or dependencies. Repo and tests:…
Life & fun · 27d ago · baselashraf81.github.io
