x8086NetEmu

A VB.NET implementation of an almost working 8086 emulator.

Although it still has some bugs, it is a fairly stable and capable 8088/86/186 emulator:

• Full 8086 architecture emulation: CPU, Memory, Flags, Registers, and Stack
• Peripherals: PIC/8259, PIT/8254, DMA/8237 and PPI/8255
• Mostly working Adapters: CGA, Speaker and Keyboard
• Partially working Adapters: VGA, Adlib, SoundBlaster and Mouse
• No BIOS hacks are required
• WinForms and Console samples included
• Cross-platform support through Mono (the emulator has been tested under Windows, MacOS, Linux, and RaspberryPi)
• Support for both Floppy and Hard Disk images
• Hard disk and floppy images inspector / Disk Explorer (FAT12, FAT16, and FAT16B/BIGDOS support only)
• Support to drag & drop files to/from the Disk Explorer and the host
• Support to copy/paste text to/from the emulator and the host
• The Emulator's menu can be accessed by pressing RCtrl+Home. Under Windows, you can also right-click the window's title bar. No menu is available in the Console version. To change the emulator's settings for the Console version you can edit the settings.dat file using any text editor
• Support to use TrueType Mono fonts, a user-provided font bitmap file, or if using a video ROM file, use the charset provided in such ROM.
• Integrated Debugger and Console

Development is currently stalled due to a breaking bug (or bugs?) which prevent the emulator from working correctly. The bug can be reproduced by booting into DOS 6.x and running EDIT, QBASIC, DEFRAG or MEMMAKER. Quite probably, this is the same bug that also prevents it from running Windows 1.01 (although Windows 2.03 almost works).

Thanks to the amazing work by @TomHarte I was able to finally find the bug that was affecting so many programs! So it happens that the TEST opcode (0x84) was using the incorrect register when in indirect mode. That was it... fixing that stupid mistake has solved all the bugs mentioned above.

Portions of the code in the emulator were adapted or inspired from 'fake86' (CGA/VGA/Adlib and SoundBlaster emulation), 'PCE - PC Emulator' (Group 2, DIV, IDIV, MUL and IMUL opcodes emulation and flags management) and 'retro' (Scheduler, chipset and keyboard handling).

Precompiled binaries can now be downloaded from the releases section.

Compiling for non-Windows platforms

The speaker emulation uses NAudio, which only works under Windows. So in order to compile a version of x8086 that works under non-Windows platforms, the Win32 custom build constant in the project properties of all the projects in the solution must be set to False.

If the aforementioned bug or bugs can be resolved, I will switch the sound backend support to the cross-platform library BASS.

Experimental Web UI

Since commit 248 the emulator can be viewed and controlled through a browser by initializing one of the WinForms video adapters with the enableWebUI parameter set to true.

cpu.Adapters.Add(New CGAWinForms(cpu, videoPort, , , True))

This will create a web server at http://localhost:8086 which uses a simple script to render the emulator's display and capture key events, which will be sent back to the emulator for processing. Mouse support is not currently available.