[![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) —
[Alpine Linux guest setup](tools/docker/alpine/) —
[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.
  - Arch Linux 32 works. See [archlinux.md](docs/archlinux.md) for building an image.
  - Debian works.
  - Ubuntu works up to the latest version that supported i386 (16.04 LTS or 18.04 LTS for some variants).
  - Alpine Linux works. An image can be built from a Dockerfile, see [tools/docker/alpine/](tools/docker/alpine/).
  - Slackware works.
  - Void 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 (only 32-bit versions).
- [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 the 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 Dev Container

- If you are using an IDE that supports Dev Containers, such as GitHub Codespaces, the Visual Studio Code Remote Container extension, or possibly others such as Jetbrains' IntelliJ 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://i.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`)