3RIC / A computer from the chips up
Build a whole computer to understand it. 3RIC is an original Apple-II-class 65C02 machine, with its own ROM, custom video logic, and a browser emulator that puts the whole thing in your hands.
Start with a one-minute graphics-and-music demo. Stay to find out how every bit works.
Opens the emulator + editor. No install. No account.
Use 1x speed; click the emulator for sound.
01 / The demo
Built from Bits is an original 65C02 program: an approximately one-minute autoplay loop at native 1x speed. Let the four scenes play through, or take over with the keyboard.
A hi-res 3RIC logo and a moving starfield. The opening signal comes from the machine’s own graphics memory.
A 16-color lo-res plasma fills a 40 × 40 mixed graphics area, with four explanatory text rows beneath it.
A rotating wireframe cube, rasterized by the CPU. Every line is drawn by the 65C02, not a GPU.
An original six-channel chiptune sequencer. Pitch and level bars reflect the actual values sent to two AY chips.
The 65C02 generates the visuals, sequences the music, and handles input. The browser hosts the emulator; there is no JavaScript animation overlay standing in for the program.
02 / Take the controls
The launch link loads the assembly into the existing editor and automatically assembles and runs it. Click the emulator screen to give it keyboard focus. You can change scenes, pause, or drop back to the monitor at any time.
03 / Under the display
3RIC began with a question: how do 8-bit computers actually work? The answer became a from-scratch machine, from chip-level schematics and address decoding to a ROM and a cycle-honest emulator. Follow the journey from the breadboard.
Video / custom logic
The hardware design generates VGA with custom logic. It reproduces NTSC-style artifact color in logic circuits, bringing the Apple II’s clever color behavior to a VGA display. The emulator models that behavior.
Memory / shared timing
The CPU and video hardware share RAM. They have to take turns on the bus: CPU reads and writes, then video fetches. Getting the timing right is what lets the processor change a picture while the display reads it.
Address bus / 74-series logic
The final build uses 74-series logic chips to decode addresses and select the memory or I/O device that responds. These are the connections behind a program’s loads and stores, built from ordinary logic chips.
C++ / WebAssembly
The same C++ VM core powers the native emulator and compiles to WebAssembly for the browser. It boots 3RIC’s real 512 KB ROM. No install or account, and no second browser-only imitation of the machine.
Beyond this demo, the wider machine supports keyboard and serial I/O, SNES pads, micro-SD, and Disk II. This program is a graphics-and-music tour, not a test of every peripheral. 3RIC is an original Apple-II-class computer with its own ROM, not a claim of blanket Apple II compatibility.
04 / Make it yours
This is not a recording you can only watch. Open the assembly that makes it happen, change a value, and let the same machine execute your version. The tools are already in the browser.
Load Built from Bits in the editor.
The shared source is programs/hackaday.s, loaded at its
declared origin, $0800.
Read the assembly on GitHub.
Edit the source and select Assemble & Run. Use the debugger to set an instruction breakpoint, step the CPU, and inspect registers or memory. The demo’s Space key pauses its score and animation; the debugger lets you stop at an instruction.
In that same editor, use Download .PRG for the raw program or Download .woz for a bootable disk image. These are editor exports, not separate prebuilt downloads. Open the editor to export your version.
05 / Follow the wires
In a sentence: 3RIC is a from-scratch, Apple-II-class 65C02 computer with custom VGA logic, its own 512 KB ROM, and a C++ emulator shared by native and WebAssembly hosts — built to learn, and documented along the way.
A whole machine. One browser tab.
Run Built from Bits