v86

Live demo.

How does it work?

v86 emulates an x86-compatible CPU and hardware. Here's a list of emulated hardware:

• An x86 compatible CPU. The instruction set is around Pentium 1 level. Some features are missing, more specifically:
  • Task gates, far calls in protected mode
  • 16 bit protected mode features and Virtual 8086 mode
  • Single stepping
  • MMX, SSE
  • A bunch of FPU instructions, FPU exceptions
  • Some other exceptions
• A floating point unit (FPU). Calculations are done with JavaScript's double precision numbers (64 bit), so they are not as precise as calculations on a real FPU (80 bit).
• An ISA bus.
• A floppy disk controller (8272A).
• A DMA (direct memory access) controller, currently only used by the FDC.
• An 8042 Keyboard Controller, PS2. With mouse support.
• An 8254 Programmable Interval Timer (PIT).
• An 8259 Programmable Interrupt Controller (PIC).
• A CMOS Real Time Clock (RTC).
• A VGA controller with SVGA support and Bochs VBE Extensions. This includes support for large resolutions.
• A PCI bus. This one is partly incomplete and not used by every device.
• An IDE disk controller.

How to build, run and embed?

• In order to build the cpu.js file, you need make and cpp (the C preprocessor). Run: make src/cpu.js.
• If you want a compressed and fast (ie, with debug code removed) version, you need Closure Compiler. Pull the submodule using

git submodule update --init --recursive closure-compiler and run make v86_all.js.

• 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.
• For more details on how to customize the behaviour and interface, see docs/adapters.md.

Why?

Similiar projects have been done before, but I decided to work on this as a fun project and learn something about the x86 architecture. It has grown pretty advanced and I just got Linux and KolibriOS working recently and there might be some actual uses.

If you build something interesting, let me know. However, keep in mind that the project is not very stable at the moment.

Compatibility

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

• Linux works pretty well. Graphical boots fails in many versions, but you mostly get a shell. The mouse is never detected automatically.
  • Damn Small Linux (2.4 Kernel): Run with lowram and choose PS2 mouse in xsetup. Takes circa 10 minutes to boot. Only works if ACPI is disabled.
  • Tinycore, Nanolinux (3.0 kernel): udev and X fail, but you get a terminal.
• FreeDOS and Windows 1.01 run pretty good. A few applications cause the OS to freeze. Some BIOS problems.
• KolibriOS works.
• Haiku boots after 30 minutes. r1alpha4 immediately reboots, the newest version compiled from source works. Requires settings the memory size to 128MB.

You get some infos on the disk images here: https://github.com/copy/v86/tree/master/images

How can I contribute?

• Someone who could work on new hardware devices, such as a modem. I'll write an overview for that at a later point, if people are interested. Also, help on the interface would be appreciated.
• Donate. Since Bitcoin is the new cool thing, here's my address: 14KBXSoewGzbQY8VoznJ5MZXGxoia8RxC9

License

Simplified BSD License, see LICENSE, unless otherwise noted.

Credits

• Test cases via QEMU, http://wiki.qemu.org/Main_Page
• https://github.com/creationix/node-sdl
• ascii.ttf (used in node) from http://www.apollosoft.de/ASCII/indexen.htm
• Disk Images

More questions?

Shoot me an email to copy@copy.sh. Please don't tell about bugs via mail, create a bug report on github instead.

Author

Fabian Hemmer (http://copy.sh/, copy@copy.sh)