retrowin32

retrowin32 is a still-early Windows emulator for the web (and other non-Windows platforms).

Take a win32 .exe file and run it in a web browser or a Mac.

See some demos.

Status

Can run a few programs, including console, win32 GUI, and DirectX. Likely will fail if given a program I haven't worked on yet.

• 2024/03: runs some of Minesweeper and more demoscene programs.
• 2023/10: preliminary support for using Unicorn (basically QEMU) for x86 emulation.
• 2023/08: new blog post about new Rosetta-based emulation support. retrowin32 now can run on web, native with CPU emulation, or Rosetta x86-64. (Native x86-64 ought to be relatively easy to add too.)
• 2023/04: "monolife" demo now can sorta render first scene.
• 2023/02: can now run natively via SDL. See blog post.
• 2022/10: released. Barely runs a few console programs and one DirectDraw program. See blog post.

See a list of blog posts for more detailed updates.

The idea

Software today is written in a world where the platform continually changes -- code you release today may stop working next year as the APIs and deprecations churn. You know what doesn't change? Dead platforms. Old video games written for a NES will work forever because the NES won't ever change again.

win32, the Windows 32-bit API, is such a platform. "win32 is the stable Linux userland ABI" is the observation that it might actually make sense for video game developers aiming for Linux to target the Windows API (which doesn't change) and rely on some translation layer to manage the Linux part (which always changes).

Today there are all these old .exe files lying around that are increasingly hard to run. Even on Windows itself, there's a 32-bit Windows translation layer when running on now standard x86-64 hardware. On non-Windows the best tool is Wine, but it still needs x86 hardware (or a CPU emulator).

So my idea is this: what if you treated a win32 executable in the same way you treat a NES ROM -- as machine code for a CPU you no longer have, expecting hardware and an OS that doesn't exist? retrowin32 is an emulator that interprets the x86 instructions and implements the Windows OS API such that a win32 executable can run directly, without the Windows OS or an x86 beneath it.

See a comparison against other Windows emulator approaches (WINE, qemu, v86) for how this is similar but different.

Running it

See HACKING.md to get started on the code.