Logic Bench is a browser-based digital-logic simulator. Drag gates onto a canvas, watch the signals glow, and run real programs. Then open every box — all the way down to one NAND.
Every box opens. Nothing inside is fake.
Six two-state logic gates, drawn with their standard distinctive shapes. This is the whole alphabet — every circuit on the bench, all the way up to the 6502, is built from these.
NAND alone is enough. Everything above is built from it.
The 6502 is the pinnacle of the climb — and even it opens. A bouncing ball runs on one built entirely from gates. Drill in, and keep going: at no level does a black box stand in for the truth.
Drag gates, switches and clocks onto a canvas. Wires glow when they carry a signal, LEDs light, displays count — and real programs run, live.
Every chip opens to the gates inside — rendered live with that instance's real signals. Looking is sealed and zero-risk. You can drill forever.
Climb from a half adder to a complete CPU — with an assembler, breakpoints, single-stepping, and your own editable memory.
There's no wrong way to start. Drop gates on a blank canvas and follow your curiosity — or take the curated path, one lesson at a time.
A blank bench and the whole component palette. Wire up a hunch, load any of the 48 built-in circuits, pack your own chips, and open every box. Nothing to set up, nothing to break.
A 63-lesson workbook — roughly 277 pages — that carries you from one switch and one lamp all the way to the 6502. Structured, hands-on, and built to stay engaging the whole climb.
The gate-built 6502 runs the same instruction set as the real chip — and we hold it to the real chip's standard.
On power-up it reads the reset vector at $FFFC, jumps there, and winds the stack pointer down to $FD — exactly as the real chip does.
Clocking ~6,000 gate nodes per cycle is too slow to animate. So RUN fast-forwards a verified-equivalent emulator, while STEP runs the actual gates — always one step from the real thing, nothing hidden.
A 48-circuit library that deliberately scales upward, plus a 63-lesson workbook — roughly 277 pages from one switch and one lamp all the way to the 6502.
Start with six gates. Each rung is built from the one below it — nothing skipped, nothing faked — until you reach the 6502 at the top.
Finally understand how a computer actually works — concretely, not by analogy. By building and opening one.
A computer-architecture course you can touch. Every abstraction — registers, ALU, flags, stack, PC — is something you build, then drill into.
A real, verified, fully dissectable 6502 in the browser — running real machine code, openable down to one gate.
Free. Runs in any browser. Nothing to install.
Start building — free, in your browser →