[![Join the chat at https://gitter.im/copy/v86](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/copy/v86) or #v86 on [irc.libera.chat](https://libera.chat/)

v86 emulates an x86-compatible CPU and hardware. Machine code is translated to
WebAssembly modules at runtime in order to achieve decent performance. Here's a
list of emulated hardware:

- An x86-compatible CPU. The instruction set is around Pentium 4 level,
  including full SSE3 support. Some features are missing, in particular:
  - Task gates, far calls in protected mode
  - Some 16 bit protected mode features
  - Single stepping (trap flag, debug registers)
  - Some exceptions, especially floating point and SSE
  - Multicore
  - 64-bit extensions
- A floating point unit (FPU). Calculations are done using the Berkeley
  SoftFloat library and therefore should be precise (but slow). Trigonometric
  and log functions are emulated using 64-bit floats and may be less precise.
  Not all FPU exceptions are supported.
- A floppy disk controller (8272A).
- An 8042 Keyboard Controller, PS2. With mouse support.
- An 8254 Programmable Interval Timer (PIT).
- An 8259 Programmable Interrupt Controller (PIC).
- Partial APIC support.
- A CMOS Real Time Clock (RTC).
- A generic VGA card with SVGA support and Bochs VBE Extensions.
- A PCI bus. This one is partly incomplete and not used by every device.
- An IDE disk controller.
- An NE2000 (RTL8390) PCI network card.
- A VirtIO filesystem.
- A SoundBlaster 16 sound card.

## Demos

[9front](https://copy.sh/v86/?profile=9front) —
[Arch Linux](https://copy.sh/v86/?profile=archlinux) —
[Android-x86 1.6-r2](https://copy.sh/v86?profile=android) —
[Android-x86 4.4-r2](https://copy.sh/v86?profile=android4) —
[BasicLinux](https://copy.sh/v86/?profile=basiclinux) —
[Buildroot Linux](https://copy.sh/v86/?profile=buildroot) —
[Damn Small Linux](https://copy.sh/v86/?profile=dsl) —
[ELKS](https://copy.sh/v86/?profile=elks) —
[FreeDOS](https://copy.sh/v86/?profile=freedos) —
[FreeBSD](https://copy.sh/v86/?profile=freebsd) —
[FiwixOS](https://copy.sh/v86/?profile=fiwix) —
[Haiku](https://copy.sh/v86/?profile=haiku) —
[SkiffOS](https://copy.sh/v86/?profile=copy/skiffos) —
[ReactOS](https://copy.sh/v86/?profile=reactos) —
[Windows 2000](https://copy.sh/v86/?profile=windows2000) —
[Windows 98](https://copy.sh/v86/?profile=windows98) —
[Windows 95](https://copy.sh/v86/?profile=windows95) —
[Windows 1.01](https://copy.sh/v86/?profile=windows1) —
[MS-DOS 6.22](https://copy.sh/v86/?profile=msdos) —
[OpenBSD](https://copy.sh/v86/?profile=openbsd) —
[Oberon](https://copy.sh/v86/?profile=oberon) —
[KolibriOS](https://copy.sh/v86/?profile=kolibrios) —
[SkiftOS](https://copy.sh/v86?profile=skift) —
[QNX](https://copy.sh/v86/?profile=qnx)

## Documentation

[How it works](docs/how-it-works.md) —
[Networking](docs/networking.md) —
[Arch Linux guest setup](docs/archlinux.md) —
[Windows 2000/XP guest setup](docs/windows-xp.md) —
[9p filesystem](docs/filesystem.md) —
[Linux rootfs on 9p](docs/linux-9p-image.md) —
[Profiling](docs/profiling.md) —
[CPU Idling](docs/cpu-idling.md)

## Compatibility

Here's an overview of the operating systems supported in v86:

- Linux works pretty well. 64-bit kernels are not supported.
  - Damn Small Linux (2.4.31 kernel) works.
  - Fedora 30 works.
  - All tested versions of TinyCore work.
  - [Buildroot](https://buildroot.uclibc.org) can be used to build a minimal image.
    [humphd/browser-vm](https://github.com/humphd/browser-vm) and
    [darin755/browser-buildroot](https://github.com/Darin755/browser-buildroot) have some useful scripts for building one.
  - [SkiffOS](https://github.com/skiffos/SkiffOS/tree/master/configs/browser/v86) (based on Buildroot) can cross-compile a custom image.
  - Archlinux works. See [archlinux.md](docs/archlinux.md) for building an image.
  - Debian works. An image can be built from a Dockerfile, see [tools/docker/debian/](tools/docker/debian/).
  - Ubuntu works up to the latest version that supported i386 (16.04 LTS or 18.04 LTS for some variants).
  - Alpine Linux works.
- ReactOS works.
- FreeDOS, Windows 1.01 and MS-DOS run very well.
- KolibriOS works.
- Haiku works.
- Android-x86 has been tested up to 4.4-r2.
- Windows 1, 3.x, 95, 98, ME, NT and 2000 work reasonably well.
  - In Windows 2000 and higher the PC type has to be changed from ACPI PC to Standard PC
  - There are some known boot issues ([#250](https://github.com/copy/v86/issues/250), [#433](https://github.com/copy/v86/issues/433), [#507](https://github.com/copy/v86/issues/507), [#555](https://github.com/copy/v86/issues/555), [#620](https://github.com/copy/v86/issues/620), [#645](https://github.com/copy/v86/issues/645))
- Windows XP, Vista and 8 work under certain conditions (see [#86](https://github.com/copy/v86/issues/86), [#208](https://github.com/copy/v86/issues/208))
  - See [Windows 2000/XP guest setup](docs/windows-xp.md)
- Many hobby operating systems work.
- 9front works.
- Plan 9 doesn't work.
- QNX works.
- OS/2 doesn't work.
- FreeBSD works.
- OpenBSD works with a specific boot configuration. At the `boot>` prompt type
  `boot -c`, then at the `UKC>` prompt `disable mpbios` and `exit`.
- NetBSD works only with a custom kernel, see [#350](https://github.com/copy/v86/issues/350).
- SerenityOS works.
- [SkiftOS](https://skiftos.org/) works.

You can get some information on the disk images here: https://github.com/copy/images.

## How to build, run and embed?

You need:

- make
- Rust with the wasm32-unknown-unknown target
- A version of clang compatible with Rust
- java (for Closure Compiler, not necessary when using `debug.html`)
- nodejs (a recent version is required, v16.11.1 is known to be working)
- To run tests: nasm, gdb, qemu-system, gcc, libc-i386 and rustfmt

See [tools/docker/test-image/Dockerfile](tools/docker/test-image/Dockerfile)
for a full setup on Debian or
[WSL](https://docs.microsoft.com/en-us/windows/wsl/install).

- Run `make` to build the debug build (at `debug.html`).
- Run `make all` to build the optimized build (at `index.html`).
- ROM and disk images are loaded via XHR, so if you want to try out `index.html`
  locally, make sure to serve it from a local webserver. You can use `make run`
  to serve the files using Python's http module.
- If you only want to embed v86 in a webpage you can use libv86.js. For usage,
  check out the [examples](examples/). You can download it from the release section.

### Alternatively, to build using docker

- If you have docker installed, you can run the whole system inside a container.
- See `tools/docker/exec` to find Dockerfile required for this.
- You can run `docker build -f tools/docker/exec/Dockerfile -t v86:alpine-3.19 .` from the root directory to generate docker image.
- Then you can simply run `docker run -it -p 8000:8000 v86:alpine-3.19` to start the server.
- Check `localhost:8000` for hosted server.

### Running via Devcontainer

- If you are using an IDE that supports Devcontainers, such as Github Codespaces, VSCode Remote Container extension, or possibly others such as Jetbrains IDEA, you can setup the development environment in a Dev container.
- Follow the instructions from your development environment to setup the container.
- Run the Task "Fetch images" in order to download images for testing.

## Testing

The disk images for testing are not included in this repository. You can
download them directly from the website using:

`wget -P images/ https://k.copy.sh/{linux3.iso,linux.iso,linux4.iso,buildroot-bzimage.bin,openbsd-floppy.img,kolibri.img,windows101.img,os8.img,freedos722.img}`

Run integration tests: `make tests`

Run all tests: `make jshint rustfmt kvm-unit-test nasmtests nasmtests-force-jit expect-tests jitpagingtests qemutests rust-test tests`

See [tests/Readme.md](tests/Readme.md) for more information.

## API examples

- [Basic](examples/basic.html)
- [Programatically using the serial terminal](examples/serial.html)
- [A Lua interpreter](examples/lua.html)
- [Two instances in one window](examples/two_instances.html)
- [Saving and restoring emulator state](examples/save_restore.html)

Using v86 for your own purposes is as easy as:

```javascript
var emulator = new V86({
    screen_container: document.getElementById("screen_container"),
    bios: {
        url: "../../bios/seabios.bin",
    },
    vga_bios: {
        url: "../../bios/vgabios.bin",
    },
    cdrom: {
        url: "../../images/linux.iso",
    },
    autostart: true,
});
```

See [starter.js](src/browser/starter.js).

## License

v86 is distributed under the terms of the Simplified BSD License, see
[LICENSE](LICENSE). The following third-party dependencies are included in the
repository under their own licenses:

- [`lib/softfloat/softfloat.c`](lib/softfloat/softfloat.c)
- [`lib/zstd/zstddeclib.c`](lib/zstd/zstddeclib.c)
- [`tests/kvm-unit-tests/`](tests/kvm-unit-tests)
- [`tests/qemutests/`](tests/qemutests)

## Credits

- CPU test cases via [QEMU](https://wiki.qemu.org/Main_Page)
- More tests via [kvm-unit-tests](https://www.linux-kvm.org/page/KVM-unit-tests)
- [zstd](https://github.com/facebook/zstd) support is included for better compression of state images
- [Berkeley SoftFloat](http://www.jhauser.us/arithmetic/SoftFloat.html) is included to precisely emulate 80-bit floating point numbers
- [The jor1k project](https://github.com/s-macke/jor1k) for 9p, filesystem and uart drivers
- [WinWorld](https://winworldpc.com/) sources of some old operating systems

## More questions?

Shoot me an email to `copy@copy.sh`. Please report bugs on GitHub.

## Author

Fabian Hemmer (https://copy.sh/, `copy@copy.sh`)
