CoCo 3 boots BASIC automatically. The CoCo 4 demos are self-booting software.
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Dial a real BBS:
Save-states:
Everything above is a real emulated machine, not a mock-up. The emulator is a
zero-dependency C++20 core — a cycle-honest 6809/6309 CPU, the GIME graphics chip,
the 6821 PIAs, a bus-mapped UART, and the CoCo 4's sprite engine, blitter, and
audio chip — compiled with Emscripten into a ~256 KB coco.wasm
that runs entirely in your browser tab.
The page boots a machine and steps it one video frame per animation tick. The canvas is the machine's own framebuffer; the BBS console is its UART output; your keystrokes go in through the emulated keyboard matrix or serial port — the same paths the real hardware used.
The CoCo 4 software you can run here (the BBS, the graphics cartridge, the terminal) is written in 6809/6309 assembly source and assembled at build time by the project's own two-pass assembler — the repository contains the whole chain, from mnemonics to the pixels you're looking at.
Save-states are a versioned binary snapshot of the entire machine (CPU + RAM + every device), POSTed to a small API on this server, so you can freeze a session and resume it later — even in a different browser.