A browser-based Philips G7000 simulator — also known as the Magnavox Odyssey² and Videopac. It emulates the console's Intel 8048 microcontroller and Intel 8244/8245 Video Display Controller entirely in JavaScript, so real cartridge dumps run in any modern browser with no plugins, no build step, and no server.
Just open index.html. There's no build step — it's plain HTML/CSS/JS, so it also
runs unmodified from GitHub Pages (see below) or any static file host.
Opening index.html from the repo's file view on github.com only shows its source —
GitHub never executes HTML/JS there. To actually run the app, serve it with
GitHub Pages (Settings → Pages → Source: Deploy from a branch → branch main,
folder / (root) → Save). This repo is already set up for it: a .nojekyll file
skips unnecessary Jekyll processing, and every path in index.html is relative, so it
works whether Pages serves it at the domain root or under a project subpath (e.g.
https://<user>.github.io/G7sim/). It also needs no server-side code — Pages' HTTPS
is exactly what the rom/rom.bin/rom.zip/games.zip auto-load and the in-browser
ZIP inflate rely on. First load takes a minute or two after enabling Pages, and again
after each push while it redeploys.
For copyright reasons no console BIOS or game ROM is bundled. You supply them at runtime — everything stays on your machine and works fully offline.
- Drop the console BIOS — the 1 KB
o2rom.bin(CRC0x8016A315). The G7400 Videopac+, French C52 and Jopac BIOSes are recognised too. - Drop a games archive — a
.zip(e.g. the ~150 KB Videopac/Odyssey² set) or a single cartridge dump (.bin/.rom). ZIPs are browsed in the library panel and inflated on demand using the browser's nativeDecompressionStream(no libraries). - Click a game in the library to play.
The BIOS and the last dropped archive are remembered (IndexedDB), so you only drop once.
If you serve the page over http(s), G7sim automatically imports rom/rom.bin
(BIOS) and rom/games.zip (game library) from next to index.html when present,
so a deployment can ship with them preinstalled. Dragged-in files are saved and take
precedence over these defaults. See rom/README.md. (Auto-load needs
http(s); on file:// use drag & drop.)
| Input | Mapping |
|---|---|
| Joystick P1 | Arrow keys · fire = Space or Left Shift |
| Joystick P2 | Numpad 8 4 6 2 · fire = Numpad 0 |
| Keyboard | Letter/number keys map to the Videopac membrane keyboard; Enter, Backspace = DEL |
Click ❓ Help at any time for a quick reference on installing ROMs, opening games, the controls, and the shortcuts.
On a touch device, tap the screen to enter fullscreen. In fullscreen and portrait orientation, touch controls appear: the screen is pinned to the top, a draggable 8-way joystick sits under the right thumb, a FIRE button under the left thumb (top-aligned with the stick), and the JOY 1/2 button in the bottom-left corner — coloured to match whichever joystick is active. Tap it to switch which one you control.
Tap the screen to pause (tap again on the dimmed screen to resume). Press and hold the screen instead to bring up a temporary number pad — e.g. for the BIOS "SELECT GAME" prompt — it closes the instant you tap a digit. Below the digits the pad carries ⌨ KEYBOARD, which opens your device's own keyboard so you can type a full hi-score name, and a row with ⟲ RESET (in most games, back to the SELECT GAME screen) and ⤢ EXIT to leave fullscreen.
The on-screen joystick snaps between its 8 discrete positions rather than sliding smoothly, matching the console's digital (not analog) stick, and gives a light haptic tap together with the FIRE button on devices that support the Vibration API. On iPhone (where the browser lacks a fullscreen API for page elements) a built-in fullscreen fallback is used automatically — including a lock against accidental pinch/double-tap zoom while it's active — so single-player games are playable on iOS Safari.
Open ⚙ Settings to turn sound on/off and adjust the volume, and to configure the two joysticks. Each joystick is shown as a D-pad-shaped diagram; use Configure all… to set its five keys in sequence (it highlights UP, DOWN, LEFT, RIGHT, FIRE in turn and you just press the key for each), or click a single direction to rebind only that one. ⇄ Flip joysticks swaps the two players' key assignments. All settings are remembered between sessions.
The modifier is Option on macOS and AltGr on Windows:
| Shortcut | Action |
|---|---|
| Alt+P | Pause / resume |
| Alt+S | Sound on / off |
| Alt+R | Reset |
| Alt+0 | Fullscreen |
| Alt+Shift+J | Flip joysticks (harder combo, to avoid accidents) |
Holding Shift while pressing a letter A–Z always types on the Videopac keyboard (handy for entering hi-score names) — even if that letter is also assigned to a joystick direction.
- CPU — full Intel 8048 (MCS-48) instruction set, timer/counter, external & timer interrupts, register banks, and the horizontal/vertical display interrupt.
- Video — 8244/8245 VDC: background & per-line colour, the 9×8 grid, single characters, quad characters, and the four sprites, with the hardware collision detection register. The original 8244 character-generator ROM and 16-colour palette are reproduced.
- Audio — the VDC's 24-bit shift-register tone/noise generator, output through Web Audio.
- Cartridge banking — 2K/4K/8K/16K and 3K/EXROM mappers, plus the per-title timing tweaks needed by many games (keyed on cartridge CRC32).
index.html markup + drop UI
src/style.css styling
src/g7000.js machine core: memory map, ports, banking, BIOS/cart loading
src/g7000-cpu.js Intel 8048 instruction interpreter
src/g7000-vdc.js 8244/8245 VDC rendering + collisions
src/g7000-audio.js audio synthesis + Web Audio sink
src/g7000-kluges.js per-cartridge timing/quirk table
src/zip.js dependency-free ZIP reader (native inflate)
src/storage.js IndexedDB persistence
src/main.js UI, input, drag & drop, run loop
The emulation reimplements, in JavaScript, the behaviour of the free O2EM emulator by Daniel Boris, André de la Rocha and Arlindo M. de Oliveira. Hardware register maps, timing constants, the 8244 character ROM and the colour palette are derived from that project. G7sim ships no copyrighted BIOS or game data.