joncampbell123/dosbox-x

Welcome to the DOSBox-X project homepage located on GitHub.

Be sure to also visit DOSBox-X's website at https://dosbox-x.com (or http://dosbox-x.software)

Discord channel for the DOSBox-X project: https://discord.gg/5cnTmcsTpG

Table of Contents

• Introduction to DOSBox-X
• Notable features in DOSBox-X
• DOSBox-X supported platforms and releases
• Compatibility with DOS programs and games
• Contributing to DOSBox-X
• DOSBox-X development and release pattern
• Future development experiments
• Software security comments
• Features that DOSBox-X is unlikely to support at this time
• Origin and history of the DOSBox-X project
• Known DOSBox-X forks
• Support for international language translations and keyboard layouts

Introduction to DOSBox-X

DOSBox-X is a cross-platform DOS emulator based on the DOSBox project (www.dosbox.com).

Like DOSBox, it emulates a PC necessary for running many MS-DOS games and applications that simply cannot be run on modern PCs and operating systems. However, while the main focus of DOSBox is for running DOS games, DOSBox-X goes much further than this. Started as a fork of the DOSBox project, it retains compatibility with the wide base of DOS games and DOS gaming DOSBox was designed for. But it is also a platform for running DOS applications, including emulating the environments to run Windows 3.x, 9x and ME and software written for those versions of Windows. By adding official support for Windows 95, 98, ME emulation and acceleration, we hope that those old Windows games and applications could be enjoyed or used once more. Moreover, DOSBox-X adds support for DOS/V and NEC PC-98 emulations so that you can play DOS/V and PC-98 games with it.

Compared with DOSBox, DOSBox-X focuses more on general emulation and accuracy. In order to help running DOS games and applications, Windows 3.x/9x/ME, as well as for the purpose of historical preservation, testing and continued DOS developments, it is our desire to implement accurate emulation, accurate enough to help make new DOS developments possible with confidence the program will run properly on actual DOS systems. DOSBox-X includes various features for different purposes (some of them ported from other projects), which are implemented as incremental changes since it was forked from DOSBox SVN Daum. DOSBox-X provides many ways to tweak and configure the DOS virtual machine, as we believe a better way to emulate the DOS platform is to give users all the options they need to emulate everything from the original IBM PC system all the way up to late 1990's configuration, whatever it takes to get your game or software package to run. Our goal is to eventually make DOSBox-X a complete emulation package that covers all pre-2000 DOS and Windows 9x based system scenarios, including peripherals, motherboards, CPUs, and all manner of hardware that was made for PC hardware of that time.

Please check out the DOSBox-X homepage for common packages of the latest release for the supported platforms, as well as screenshots of some DOS programs and games running in DOSBox-X. Also see the INSTALL page for DOSBox-X installation instructions and other packages, and the Releases page for archives of all released DOSBox-X versions. For more information about DOSBox-X, such as setting up and running DOSBox-X including its usage tips, please read the user guide in the DOSBox-X Wiki. Steps for building the source code can be found in the BUILD page.

DOSBox-X is completely open-source and free of charge to use and distribute. It is released under the GNU General Public License, version 2. See also the About DOSBox-X page for more information about DOSBox-X's goals and non-goals, along with some links to other projects.

This project has a Code of Conduct, please read it for general information on contributing to or getting support from the project.

Brought to you by: joncampbell123 (Jonathan Campbell)

Notable features in DOSBox-X

Although based on the DOSBox project, DOSBox-X is now a separate project because both have their own separate schedules and development priorities. For example, the main focus of DOSBox is for running DOS games whereas DOSBox-X goes way beyond this. At this time DOSBox-X already has a great number of features that do not exist in DOSBox. Examples of such features include:

• GUI drop-down menu and built-in graphical configuration tool

• Save and load state support (with up to 100 save slots + save files)

• NEC PC-98, AX, DOS/V emulation and Chinese/Japanese/Korean support

• Fully translatable user interfaces (with language files available)

• Better support and compatibility with DOS applications

• Support for more DOS commands and built-in external tools

• Support for different ways to customize the internal Z: drive

• Support for CPU types like Pentium Pro, II, III and MMX instructions

• Support for IDE interfaces and improved Windows 3.x/9x emulation

• Support for long filenames and FAT32 disk images (DOS 7+ features)

• Support for pixel-perfect scaling output for improved image quality

• Support for TrueType font (TTF) output for text-mode DOS programs

• Support for printing features, either to a real or to a virtual printer

• Support for starting programs to run on the host systems (-hostrun option)

• Support for 3dfx Voodoo chip and Glide emulation (including Glide wrapper)

• Support for cue sheets with FLAC, MP3, WAV, OGG Vorbis and Opus CD-DA tracks

• Support for FluidSynth MIDI synthesizer (with sound fonts) and MT-32 emulation

• Support for NE2000 Ethernet for networking features and modem phone book mapping

• Support for features such as V-Sync, overscan border and stereo swapping

• Plus many more..

While the vast majority of features in DOSBox-X are cross-platform, DOSBox-X does also have several notable platform-dependent features, such as Direct3D output and support for automatic drive mounting on the Windows platform. These features cannot be easily ported to other platforms. More information about DOSBox-X's features can be found in DOSBox-X’s Feature Highlights page in the DOSBox-X Wiki.

DOSBox-X officially supports both SDL 1.2 and SDL 2.0; both 32-bit and 64-bit builds are also supported.

DOSBox-X supported platforms and releases

DOSBox-X is a cross-platform DOS emulator, so all major host operating systems are officially supported, including:

1. Windows (XP or higher), 32-bit and 64-bit

2. Linux (with X11), 32-bit and 64-bit

3. macOS (Mac OS X), Intel and ARM-based 64-bit

4. DOS (MS-DOS 5.0+ or compatible)

Windows binaries (both 32-bit and 64-bit), Linux Flatpak or RPM packages (64-bit), macOS packages (64-bit) and DOS versions are officially released periodically, typically on the last day of a month or the first day of the next month. Please check out the DOSBox-X homepage and the INSTALL page for the latest DOSBox-X packages on these platforms and further installation instructions. You can also find ZIP packages or Windows installers for all released versions and their change logs in the Releases page. The Window installers are intended to ease the installation process, and they allow you to start DOSBox-X as soon as the installation ends.

For running DOSBox-X in a real DOS system (MS-DOS or compatible), you can find the HX-DOS package that makes use of the freely-available HX DOS Extender. Type DOSBOX-X to run it from a DOS system. There is also the DOS LOADLIN package which can run from within DOSBox-X itself in addition to a DOS system. Note, however, that not all features of DOSBox-X that are supported in other platforms can be supported in the real DOS environment.

Development (preview) builds intended for testing purposes for various platforms are also available from the DOSBox-X Development Builds page.

The full source code is officially provided with each DOSBox-X release, which may be compiled to run on the above and possibly other operating systems too. You can also get the latest development source code from the repository directly. See also the BUILD page for information on building/compiling the DOSBox-X source code.

Compatibility with DOS programs and games

With the eventual goal of being a complete DOS emulation package that covers all pre-2000 DOS and Windows 3.x/9x based hardware scenarios, we are making efforts to ensure that the vast majority of DOS games and applications will run in DOSBox-X, and these include both text-mode and graphical-mode DOS programs. Microsoft Windows versions that are largely DOS-based (such as Windows 3.x and 9x) are officially supported by DOSBox-X as well. Note that certain config settings may need to be changed from the default ones for some of these programs to work smoothly. Take a look at the DOSBox-X Wiki for more information.

Efforts are also made to aid continued DOS developments by attempting to accurately emulate the hardware, which is why DOSBox-X used to focus on the demoscene software (especially anything prior to 1996) because that era of the MS-DOS scene tends to have all manner of weird hardware tricks, bugs, and speed-sensitive issues that make them the perfect kind of stuff to test emulation accuracy against, even more so than old DOS games. But without a doubt we are also making a lot of efforts to test DOSBox-X against other DOS games and applications, as well as PC-98 programs (most of them are games).

We add new features and make other improvements in every new DOSBox-X version, so its compatibility with DOS programs and games are also improving over time. If you have some issue with a specific DOS program or game, please feel free to post it in the issue tracker.

Contributing to DOSBox-X

We encourage new contributors by removing barriers to entry. Ideas and patches are always welcome, though not necessarily accepted.

If you really need that feature or change, and your changes are not accepted into this main project (or you just want to mess around with the code), feel free to fork this project and make your changes in your fork.

As joncampbell123 only has limited time to work on DOSBox-X, help is greatly appreciated:

• Testing
  • Features of DOSBox-X, such as its commands and functions
  • The normal operation of DOS games and applications
  • Windows 1.0/2.x/3.x & Windows 95/98/ME guest system support
  • Software or hardware emulation accuracy, helped by for example demoscene software
  • Write more unit tests to test various functions (see existing unit tests in tests/)
  • Developments of new DOS software (possibly aided by DOSLIB/DOSLIB2)
• Bug fixes, patches, improvements, refinements
• Suggestions, ideas, assistance of other users, and/or general conversation
• Platform support (Windows, Linux, macOS, DOS, but others are welcome)
• Documentation, language file translation, and software packaging
• Notes regarding DOS and Win3.x/9x games, applications, hacks or weird tricks, etc.

See the CONTRIBUTING page for more contribution guidelines. If you want to tweak or write some code and you don't know what to work on, feel free to visit the issue tracker to get some ideas.

For more descriptions on the source code, please take a look at the DOSBox-X source code description page. Information on building on the source code can be found in the BUILD page.

Information about the debugger is also available in the DOSBox-X Debugger page.

See also the CREDITS page for crediting information.

DOSBox-X development and release pattern

In order to make DOSBox-X's development process more smooth, we have implemented a general development/release pattern for DOSBox-X. The current release pattern for DOSBox-X is as follows:

New DOSBox-X versions are made public at the start (typically on the first day) of each month, including the source code and binary releases. Then the DOSBox-X developments will be re-opened for new features, pull requests, etc. There will be no new features added 6 days before the end of the month, but only bug fixes. The last day of the month is DOSBox-X’s build day to compile for binary releases the first of the next month, so there will be no source code changes on this day including pull requests or bug fixes.

For example, suppose August is the current month - August 25th will be the day pull requests will be ignored unless only bug fixes. August 31st (the last day of August) will be DOSBox-X build day.

This is DOSBox-X’s official release pattern, although it may change later.

Future development experiments

Scattered experiments and small projects are in experiments/ as proving grounds for future revisions to DOSBox-X and its codebase.

These experiments may or may not make it into future revisions or the next version.

Comments are welcome on the experiments, to help improve the code overall.

There are also patches in patch-integration/ for possible feature integrations in the future. We have already integrated many community-developed patches into DOSBox-X in the past.

See also General TODO.txt for some plans of future DOSBox-X developments.

Software security comments

DOSBox-X cannot claim to be a "secure" application. It contains a lot of code designed for performance, not security. There may be vulnerabilities, bugs, and flaws in the emulation that could permit malicious DOS executables within to cause problems or exploit bugs in the emulator to cause harm. There is no guarantee of complete containment by DOSBox-X of the guest operating system or application.

If security is a priority, then:

Do not use DOSBox-X on a secure system.

Do not run DOSBox-X as root or Administrator.

If you need to use DOSBox-X, run it under a lesser privileged user, in a chroot jail or sandbox, or enable DOSBox-X's secure mode with its command-line option -securemode, which disables commands that may allow access to the host system.

If your Linux distribution has it enabled, consider using the auditing system to limit what the DOSBox-X executable is allowed to do.

Features that DOSBox-X is unlikely to support at this time

DOSBox-X aims to be a fully-featured DOS emulation package, but there are some things the design as implemented now cannot accommodate.

• Pentium 4 or higher CPU level emulation.

  DOSBox-X contains code only to emulate the 8086 through the Pentium III. Real DOS systems (MS-DOS and compatibles) also work best with these CPUs.

  If Pentium 4 or higher emulation is desired, consider using a PC emulator like Bochs or QEMU instead. DOSBox-X may eventually develop Pentium 4 emulation, if wanted by the DOSBox-X community in general.

• Emulation of PC hardware 2001 or later.

  The official cutoff for DOSBox-X is 2001, when updated "PC 2001" specifications from Microsoft mandated the removal of the ISA slots from motherboards. The focus is on implementing hardware emulation for hardware made before that point.

  Contributors are free to focus on emulating hardware within the time frame between 1980 and 2000/2001 of their choice.

• Windows guest emulation, Windows Vista or later.

  DOSBox-X emulation, in terms of running Windows in DOSBox-X, will focus primarily on Windows 1.0 through Windows ME (Millennium Edition), and then on Windows NT through Windows XP. Windows Vista and later versions are not a priority and will not be considered at this time. These versions of Windows are not based on DOS.

  If you need to run Windows XP and later, please consider using QEMU, Bochs, VirtualBox, or VMware.

• Any MS-DOS system other than IBM PC/XT/AT, AX, Tandy, PCjr, and PC-98.

  Only the above listed systems will be considered for development in DOSBox-X. This restriction prevents stretching of the codebase to an unmanageable level and helps keep the code base organized.

  It would be easier on myself and the open source community if developers could focus on emulating their platform of interest in parallel instead of putting everything into one project that, most likely, will do a worse job overall emulating all platforms. However, if adding emulation of the system requires only small minimal changes, then the new system in question may be considered.

  You are strongly encouraged to fork this project and implement your own variation if you need to develop MS-DOS emulation for any other system or console. In doing that, you gain the complete freedom to focus on implementing the particular MS-DOS based system of interest, and if desired, the ability to strip away conflicting IBM PC/XT/AT emulation and unnecessary code to keep your branch's code manageable and maintainable.

  If you are starting a fork, feel free to let me know where your fork is and what system it is emulating, so I can list it in this README file for others seeking emulation of that system. To help, I have added machine and video mode enumerations as "stubs" to provide a starting point for your branch's implementation of the platform. A stub implemented so far is "FM Towns emulation" (machine=fm_towns).

• Cycle-accurate timing of x86 instructions and execution.

  Instructions generally run one per cycle in DOSBox-X, except for I/O and memory access.

  If accurate emulation of cycles per instruction is needed, please consider using PCem, 86Box, or VARCem instead.

• Full precision floating point emulation.

  Unless using the dynamic core, DOSBox and DOSBox-X emulate the FPU registers using the "double" 64-bit floating point data type.

  The Intel FPU registers are 80-bit "extended precision" floating point values, not 64-bit double precision, so this is effectively 12 bits of precision loss and 5 bits of range loss (64 to 53 mantissa bits and 16 to 11 exponent bits). This slight loss of precision is perfectly fine considering DOSBox's original goal in supporting DOS games, but may cause problems in other cases that need the full precision.

  It is known at this time that this lack of precision is enough to cause otherwise straightforward comparisons against integers to fail in DOS applications originally written in QBasic or Turbo Basic. There are such DOS games written that check their file size using a floating point compare that will fail in this manner. To run these games, you will need to disable FPU emulation (fpu=false) to force the QBasic/TurboBasic runtime to use software emulation instead.

Origin and history of the DOSBox-X project

DOSBox-X started as a fork of the original DOSBox project sometime in mid-2011. It was started out of a desire to improve the emulator without having to fight with or worry about submitting patches upstream.

As its developers have made it clear, DOSBox's main focus is on DOS games. This is evident by the fact that much of the code is somewhat accurate code with kludges to make DOS games run, instead of focusing on the actual behaviors of real DOS systems.

Jonathan Campbell, the DOSBox-X project maintainer wanted to make various changes to the source code, but many of them were non-game related, and thus were unlikely to be accepted by the DOSBox developers.

Since then, Jonathan Campbell has been modifying the source code over time to improve emulation, fix bugs, and resolve incompatibilities with Windows 95 through ME. He has added options so that DOSBox-X by default can emulate a wider variety of configurations more accurately, while allowing the user to enable various techniques or hacks if needed to run their favorite DOS games or programs. He has also been cleaning up and organizing the code to improve stability and portability where possible.

The original DOSBox project was not written by one programmer. It has been under development since late 2000 with patches, fixes, and improvements from members all over the Vogons forums. Despite not having a major official release since DOSBox 0.74 over 10 years ago, the project is still in semi-active development today in the form of DOSBox SVN. Meanwhile, some of the changes themselves incorporated code from other projects.

Some features and improvements in DOSBox-X also came from another branch of DOSBox known as DOSBox SVN Daum which itself incorporated features from the original DOSBox project, DOSBox-X, and many experimental patches. Although the Daum branch seems to be dead, the features borrowed from it still exists in DOSBox-X. Later on, DOSBox-X also incorporated several features and improvements from other projects such as DOSBox ECE, DOSBox Staging, DOSVAX/DOSVAXJ3, and vDosPlus.

The DOSBox-X project is also helped by its other developers and contributors such as Wengier, aybe, Allofich, and rderooy, who have done significant work to improve the DOSBox-X project, including adding new features, fixing bugs, creating the documentation, maintaining the website, and porting code from other projects.

See also the CREDITS page for crediting of the source code.

Known DOSBox-X forks

• DOSBox-X Emscripten port (runnable in a web browser) by Yksoft1

  Significant changes are made in order to run efficiently within the web browser when compiled using LLVM/Emscripten. These significant changes require dropping some useful features (including the menus) but are required for performance.

  URL: https://github.com/yksoft1/dosbox-x-vanilla-sdl/tree/emscripten (look for clone URL and use the emscripten branch)

• DOSBox-X-App (for Windows and macOS) by emendelson

  DOSBox-X-App is a slightly customized version of DOSBox-X, combined with external programs and commands that make it easy to print and create PDFs from DOS applications. It is customized for use with applications, not games.

  URL: http://www.columbia.edu/~em36/dosboxapp.html

• DOSBoxWP (for WordPerfect for DOS) by emendelson

  DOSBoxWP is a customized version of DOSBox-X targeted for users of WordPerfect for DOS.

  URL (Windows): http://www.columbia.edu/~em36/wpdos/dosboxwp.html

  URL (macOS): http://www.columbia.edu/~em36/wpdos/wpdosboxmac.html

• Win31DOSBox (Windows 3.1 for 64-bit Windows) by emendelson

  Win31DOSBox aims to be an easy method of running Windows 3.x software for 64-bit Windows systems. The system uses a custom build of DOSBox-X when running Windows 3.1x.

  URL: http://www.columbia.edu/~em36/win31dosbox.html

Support for international language translations and keyboard layouts

DOSBox-X displays English as the default language, and uses the U.S. code page (437) by default, just like DOSBox.

All messages displayed by DOSBox-X are in English with the default setting. DOSBox-X does support the feature to change the display messages with the use of language files. The language files control all visible output of the internal commands and the internal DOS, as well as the text in DOSBox-X's drop-down menus. If you are a speaker of a non-English language, you are encouraged to create additional language files for use with DOSBox-X by translating messages in DOSBox-X to your language. Other DOSBox-X users can also use these language files for DOSBox-X to display messages in such languages. There are several language files available in the DOSBox-X repository, e.g.:

The fact that DOSBox-X was developed around the U.S. keyboard layout is primarily due to limitations around the SDL1 library which provides input handling. As such when using the SDL1 version and a non-US keyboard, DOSBox-X automatically uses scancodes with the default setting to work around keyboard layout issues. Scancodes are not needed when using non-US keyboard layouts in the SDL2 version. If you find that a keyboard layout is not yet supported by DOSBox-X, in order to add additional layouts for use with DOSBox-X, please see file README.keyboard-layout-handling on how to do so as a developer.

For further information on international support and regional settings of DOSBox-X, such as steps to create DOSBox-X language files or use external keyboard files in DOSBox-X, as well as support for the Euro symbol and country-specific date and time formats, please look at the guide Regional settings in DOSBox-X in the DOSBox-X Wiki. For more information on East Asian (Chinese/Japanese/Korean) language support, see the East Asian language and system support guide page.