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XTulator - A portable, open source (GPLv2) 80186 PC emulator

About

XTulator is an x86 PC emulator that is designed to run software that was written for Intel processors up to the 80186. It's able to run MS-DOS, FreeDOS, Windows 3.0, and many games of the era. It supports graphics up to the EGA/VGA standard, and emulates the Sound Blaster 2.0 as well as Adlib/OPL2 (using Nuked OPL). It also emulates peripherals like the standard Microsoft-compatible serial mouse and a serial modem, which can simulate phone line connections via TCP. An NE2000 Ethernet adapter is also emulated using pcap.

This is actually a rewrite of an emulator I wrote many years ago. It was poorly implemented, even though it worked fairly well. It had many hacks and a poor architecture, but most old 80186 software could still run under it. I've just never quite been happy with it, so I am writing this new emulator to be more sanely coded, and more accurate. I'm aiming to create a much more modular architecture this time around and avoid the design flaws which turned the old code into a mess.

Re-write goals

• More sane architecture in general
• Minimize (preferably eliminate) use of shared globals
• Implement a sort of generic "virtual ISA card" interface
• Keep CPU and other modules as independent of each other as possible
• Improve accuracy of chipset and components emulation
• Maintain host platform-independence
• Implement proper hard drive and floppy disk controller interfaces, rather than "cheating" with HLE like before

Current status

WARNING: This software is still currently in the early stages, and not really ready for general use. If you enjoy testing experimental new software, this is for you!

It supports multiple machine definitions which are selectable via the command line. (-machine option, use -h for help) Only the "generic_xt" machine is currently bootable. This is currently making use of the Super PC/Turbo XT BIOS from phatcode.net which is attributed to Ya'akov Miles and Jon Petrosky.

I hope to get the stock IBM XT and other BIOSes bootable in the near future. They don't seem to like something about my chipset implementation, which is my highest priority bug at the moment.

You cannot change floppy images on the fly yet unless you're using the Windows build. I'm trying to come up with a cross-platform GUI method to do this and change other options in real-time. If you need to install an OS and programs on a hard disk image under Linux/Mac, it may be best for now to do that in something like QEMU or Fake86, and then boot the HDD image in XTulator.

Checkmarks below mean that feature is implemented enough to boot and run things with the "generic_xt" machine definition. See comments below for details.

• CPU - Complete
• Implement support for multiple machine defnitions (This exists, but only the generic_xt machine boots, the other BIOSes have issues. This is a high priority thing to fix)
• Intel 8253 timer (Re-implemented, but needs some work to be fully accurate)
• Intel 8259 interrupt controller (Working, also needs some more attention. This may be the cause of some of the BIOS issues.)
• Intel 8237 DMA controller (Partially implemented, same as above regarding BIOS boot issues)
• Intel 8255 PPI controller
• Re-implement proper system timing
• Re-implement proper video rendering
• Rewrite and improve EGA/VGA handling from old emulator (EGA/VGA works now, with some bugs)
• Implement proper IDE and floppy controller interfaces (Work begun on FDC)
• Keyboard input
• Mouse input
• PC speaker (Works, but need to figure out why RealSound doesn't work in Links)
• Adlib/OPL2 (Using Nuked OPL for now. Still working on my own OPL code, which is making noises, but not good noises.)
• Sound Blaster (SB 2.0 compatibility, but still need to add high speed DMA mode. Glitches with a couple of games I've tried, working on it...)
• RTC (Need to fix this under non-Win32 OSes)
• Emulate a Hayes-compatible a serial modem using TCP (somewhat working, only in Windows)
• Novell NE2000 ethernet (Adapted source from Bochs)
• Implement Intel 8080 emulation in the NEC V20 mode (low priority)

Pre-compiled Win32 release

You can download a pre-compiled Win32 binary by clicking here. It's v0.20.7.15 pre-alpha. It also includes a sample hard disk image with some very old shareware to test with, as well as the public domain BIOS ROM for the generic_xt machine. To use the NE2000 Ethernet emulation, you will need to install Npcap.

Compiling from source

This project has been tested to compile in Visual Studio 2019, Debian 10 and MacOS, though I may occasionally break Linux/MacOS support as it's not my main platform and I don't always test it at this point. Don't be surprised if it crashes and burns. Interpret "committed to master" as "this worked on Windows" for the time being.

Windows (Visual Studio 2019)

The repository includes a Visual Studio 2019 solution and project. You will need to install the SDL2 and Npcap dev libraries.

Linux

Sorry, there's no configure script or makefile yet, so you'l have to compile and link it by hand.

You will need the SDL2 and pcap dev libraries. On Debian/Ubuntu and related distributions, you can install it with the following line.

After this, the following line should successfully compile the code.

Some screenshots