Aeon is an x86 with DOS emulator written in 100% C#. It was originally started in 2008 as an experiment in developing a high performance emulator fully in C#/.NET. So basically, it's like DOSBox but with worse compatibility and only for Windows.

C# developers might be interested in this, or fans of retro gaming that want to experiment with a different emulator. If you're just looking to get an old game running, just use DOSBox :)

See the Releases page for the latest builds, or get the source and build it yourself (see building instructions below).

Aeon doesn't have an installer, but does require that the .NET 6 runtime is installed. You can download it from Microsoft at https://dotnet.microsoft.com/download/dotnet/6.0.

The easiest way to get started is just to use the "quick launch program" button in the toolbar, and browse to a DOS .exe or .com file. Launching a program this way will create a virtual environment with the program's directory mounted as the C: drive in the emulated system.

It's also possible to quick launch a command prompt in a directory if you'd like to pass in arguments before launching the program. Batch files are supported.

You can set up the emulated environment with more detail by creating a json configuration file with a .AeonConfig extension and launching it with the quick launch program button. This format isn't documented yet, but you can find a few basic samples in the repo.

Aeon aims to emulate the hardware and software environment of a typical 486DX PC, which was pretty common in the early 1990s. The following is currently emulated:

• CPU
  • Core x86 Instruction Set
    • Nearly all instructions are implemented, but there are still some gaps (generally, I've only implemented new instructions as I find old programs that use them)
  • x87 FPU (floating point unit/instructions)
    • Not emulated with true precision (Aeon uses 64-bit floating point math rather than the 80-bit format used in the original x87)
• Memory
  • Real Mode Memory Model
  • Protected Mode Memory Model
    • Still a number of bugs in this, but it is adequate to run most DOS applications that used common DPMI extenders
• Video
  • Text modes: 80x25, 40x25
  • Graphical modes:
    • CGA (320x200 4-color mode 04h)
    • EGA (320x200, 640x200, 640x320 16-color modes 0Dh, 0Eh, 10h)
    • VGA (640x480 4-color, 320x200 256-color modes 12h, 13h)
    • Unchained 13h VGA (mode X)
    • SVGA VBE 2.0 (linear and windowed)
  • Display filtering: Scale2x, Scale3x
• BIOS/System
  • 8259 interrupt controller
  • 8253/8254 interrupt timer
• Peripherals
  • PS2 keyboard + interrupt handler
  • PS2 mouse + interrupt handler + mouse driver
  • Game port
    • Limited, currently only using DirectInput/XInput
• DOS
  • Roughly equivalent to MS-DOS 5.0
  • Command/batch interpreter
  • Mountable drives:
    • Host directory
    • ISO image
    • BIN/CUE image
    • Host CD drive
• Sound
  • Internal PC speaker
    • Timer-based waveform generation only, no direct access
  • OPL3/Ymf262 FM sythesis (Sound Blaster, Adlib)
  • Sound Blaster 16 DSP
    • Primarily Single/auto DMA mode
  • General MIDI using any of:
    • Windows MIDI Mapper
    • MeltySynth SoundFont-based MIDI synthesis (requires SoundFont)
    • mt32emu Roland MT-32 emulation (requires MT32 roms)

You can build Aeon using Visual Studio 2022. It has a couple NuGet dependencies that should be fetched automatically on build.

Important: Aeon will be extremely slow if you build in Debug configuration, and even in a Release configuration if you have a debugger attached, as it relies heavily on inlining, intrinsics, and other JIT compiler optimizations that get suppressed in Debug mode or with a debugger attached.