The latest version of the openMSX manual can be found on the openMSX home page:
You can also use this URL to get up-to-date versions of the hyper links if you printed out this manual.
This guide is about openMSX, the open source MSX emulator that tries to achieve near-perfect emulation by using a novel emulation model. You can find more information about openMSX on the openMSX home page. You can also download the emulator itself from there.
This guide describes the setup of openMSX. After installation, openMSX is ready to run using C-BIOS and the default settings. In this guide you can read how to configure openMSX to emulate actual MSX machines (such as Panasonic FS-A1GT). It also describes how you can have openMSX start up with your personal settings, how you can configure openMSX and your system for optimal performance and several other configuration related topics.
Disclaimer: We do not claim this guide is complete or even correct. What you do with the information in it is entirely at your own risk. We just hope it helps you enjoy openMSX more.
The following people contributed to this document in one way or another:
Thanks to all of them!
For the revision history, please refer to the commit log.
We use the word machine to refer to a specific MSX model. For example, the Sony HB-75P is a machine. openMSX does not have a fixed machine hardcoded into it. Instead, many different MSX machines can be emulated. The details of a machine are described in an XML file. This file describes how much memory a machine has, what video processor it has, in which slots its system ROMs are located, whether the machine has a built-in disk drive etc. openMSX reads the machine description XML and will then emulate exactly that MSX machine, which can be anything from an MSX1 with 16 kB of RAM to the MSXturboR GT.
The openMSX distribution contains XML files describing many existing MSX
You can find them in the
If you want to run one of those machines,
you also need the system ROMs for that machine.
See the next chapter for more
information on system ROMs.
You can also create your own machine descriptions,
to expand existing MSX models or to create your own fantasy MSX. There are currently some of such fantasy MSX machines, based on real MSX machines, shipped with openMSX. Examples are a machine called "Boosted_MSX2_EN" (a European MSX2 with loads of hardware built in) and one called "Boosted_MSX2+_JP" (a Japanese MSX2+ with loads of hardware built in). You can find some more information about them in their accompanying txt file in
More about creating fantasy MSX machines in a
An extension is a piece of MSX hardware that can be
inserted into a cartridge slot to extend the capabilities of an MSX.
Examples of extensions are the Panasonic FMPAC, the Sunrise IDE interface
and an external 4MB memory mapper.
Extensions, like machines, are described in XML files.
You can find a lot of predefined extensions
Some extensions need ROM images in order to run, similar to system ROMs.
In general, the XML files that describe the hardware configuration are called "hardware configuration XML files".
An MSX machine consists of a lot of hardware, but also contains some software. Such software includes the BIOS, MSX-BASIC, software controlling disk drives and built-in applications (firmware). openMSX emulates the MSX hardware, but it needs MSX system software to emulate a full MSX system. Because the internal software is located in ROM chips, it is referred to as system ROMs.
The software in the system ROMs, like most software, is copyrighted. Depending on your local laws, there are certain things you are allowed to do with copyrighted software and certain things you are not allowed to do. In this manual, a couple of options are listed for providing system ROMs to your openMSX installation. It is up to you, the user, to select an option that is legal in your country.
C-BIOS stands for "Compatible BIOS". It tries to be compatible with the MSX BIOS found in real MSX machines, but it was written from scratch, so all copyrights belong to its authors. BouKiChi, the original author of C-BIOS, was kind enough to allow C-BIOS to be distributed together with openMSX. Since then, Reikan took over maintenance of C-BIOS and the license was changed to give users and developers even more freedom in using C-BIOS. Even later, C-BIOS was moved to a SourceForge.net project, with several new maintainers. Every now and then, an updated version of C-BIOS is released. You can wait for it to be included in the next openMSX release, or download it directly from the C-BIOS web site.
C-BIOS can be used to run most MSX1, MSX2 and MSX2+ cartridge-based games. It does not include MSX-BASIC and does not support disk drives yet, so programs depending on that will not run. So, with the C-BIOS machines and ROMs that came with openMSX, you cannot run software that comes on tape, disk or any other media than cartridges with ROMs.
openMSX contains several machine configurations using C-BIOS.
C-BIOS_MSX1 is an MSX1 with 64 kB RAM.
C-BIOS_MSX2 is an MSX2 with 512 kB RAM and 128 kB VRAM.
C-BIOS_MSX2+ is an MSX2+ with 512 kB RAM, 128 kB VRAM and MSX-MUSIC.
The latter is the default machine for openMSX after installation,
so if you change nothing to the openMSX configuration,
C-BIOS_MSX2+ is the machine that will be booted. The
mentioned machines have a US English (international) keyboard layout and
character set and run at 60Hz (like NTSC) interrupt frequency. From C-BIOS
0.25, there are also localized versions available: Japanese, European (like US,
but 50Hz) and Brazilian types. You can recognize them easily.
It is always legal for you to run the C-BIOS ROMs in openMSX.
You are allowed to use C-BIOS and its source code in various other ways
as well, read the C-BIOS license for details.
It is located in the file
README.cbios in the Contrib directory.
If you own a real MSX machine, you can dump the contents of its system ROMs to create ROM images you can run in openMSX. This way, you can emulate the MSX machines you are familiar with.
The easiest way to dump system ROMs is to run a special dumping tool on your real MSX, which copies the contents of the system ROMs to disk. Sean Young has made such tools, you can find the tools and documentation on BiFi's web site. These tools can also be used to dump cartridge ROMs, which may be useful later, if you want to use certain extensions or play games.
Using ROMs dumped from machines you own is generally considered a proper thing to do in the MSX community. When the MSX machine was bought in a shop years ago, you or the person that originally bought it paid money for the MSX machine. A small part of that money paid for the software in the system ROMs. However, we are no legal experts, so it is up to you to check whether it is legal in your country to use dumped ROMs of machines you own.
Some WWW and FTP sites offer MSX system ROMs as a download. Some MSX emulators include system ROMs in their distribution. Downloaded system ROMs can be used in the same way as system ROMs you dumped yourself, see the previous section.
It may be illegal in your country to download system ROMs. Please inform yourself of the legal aspects before considering this option. Whatever you decide, is your own responsibility.
If you want to emulate real MSX machines next to the default C-BIOS based machines, you will have to install system ROMs that did not come with openMSX. This section explains how to install these, once you obtained them in one of the ways that are explained in the previous sections.
The easiest way is to copy the ROM files in a so-called file pool: a special
directory where openMSX will look for files (system ROMs, other ROMs, disks,
tapes, etc.). The default file pool for system ROMs is the
systemroms sub directory. The best way is to make a
systemroms sub directory in your own user directory, which is
|Windows (e.g. Windows 7)|
|Unix and Linux|
Please note that the path part which comes before
share can be
overridden by setting the
OPENMSX_HOME environment variable, see the chapter about User Preferences.
That way, you do not need special privilages. Furtermore, the installer won't touch them for sure on Windows nor on Android.
A template for
systemroms sub directory is present in the installation
directory of openMSX, which is also platform dependent:
|Platform||Typical openMSX file pool installation directory|
|Windows (any version)|
|Unix and Linux|
So, you can just copy all your system ROMs to the
share/systemroms directory of your user account. The ROM files can
be zipped (or gzipped), but only one file can be in a ZIP file. If multiple ROM
files are in a single ZIP file, openMSX will not find them. The directory
share/systemroms is not relevant, openMSX will
search completely through it.
More info about file pools is in the documentation of the
filepool command. If
you can't get this working, please read one of the next sections about
For advanced users, it is also possible to let openMSX load a specific set
of ROM images for a machine, independent of any file pool or the checksums of
the ROM images. For that you copy the ROM file with the name and path as
mentioned in the hardware configuration XML file that describes the machine,
relative to the path of that machine description file. For example, if you
dumped the ROMs of a Philips NMS 8250 machine, copy them to
share/machines, because in the machine description file (in
share/machines/Philips_NMS_8250.xml) the name of the ROMs is like
nms8250_msx2sub.rom. We recommend to not use this feature,
but use the file pools as mentioned above.
All necessary system ROM files used in machines and extensions are
primarily identified with a checksum: a sha1sum. This enables openMSX to find
the right ROM file from one of the file pools of type
without depending on the file name. So the actual content is guaranteed to be
what was intended. If the ROM is explicitly specified in the configuration file
(which is also supported) and the sha1sum doesn't match, a warning will be
If you are trying to run an MSX machine and get an error like
error: Error in "broken" machine: Couldn't find ROM file for "MSX BIOS with
BASIC ROM" (sha1: 12345c041975f31dc2ab1019cfdd4967999de53e). it means
that the required system ROM for that machine with the given sha1sum cannot be
found in one of the file pools as mentioned above (typically
share/systemroms). This is the primary way to know that you are
missing required system ROMs and thus something went wrong installing them
(typically either not a file with the proper content or you put the file in the
wrong place, or you put it in a large ZIP file with multiple files).
You can also manually check whether you have the correct ROM images. The
value in the <sha1> tag(s) in the hardware configuration XML files
contain checksums of ROM images that are known to work. You can compare the
checksums of your ROM images to the ones in the hardware configuration XML
files with the
sha1sum tool. It is installed by default on most
UNIX systems, on Windows you would have to download it separately. If the
checksums match, it is almost certain you have correct system ROMs. If the
checksums do not match, it could mean something went wrong dumping the ROMs, or
it could mean you have a slightly older/newer model which contains different
A typical case in which you can have problems with checksums (or ROMs not getting found in a file pool) is disk ROMs. The ROM dump can be correct, and still have a different checksum. This is because part of the ROM is not actually ROM, but mapped on the registers of the floppy controller. When you are sure it is correct, don't put it in a file pool, but put it in the proper directory, which is explained above. Alternatively, you could add the checksum in the XML file that describes the machine you made the ROM dump for (multiple checksums can be present, they will be checked in the same order as they are in the file).
The machine configurations bundled with openMSX often refer to ROM files that span multiple 16 kB pages. For example, in the NMS 8250 configuration, the BIOS and MSX-BASIC are expected in a single 32 kB ROM image. If you created two 16 kB images when dumping or got those from downloading, you can concatenate them using tools included with your OS. In Linux and other Unix(-like) systems you can do it like this:
In Windows, open a command prompt and issue this command:
The Pioneer PX-7 and Pioneer PX-V60 are both emulated including an emulated Laserdisc Player, making it possible to run Palcom Laserdisc software.
The laserdisc must be captured before it can be used with an emulator. The file must adhere to the following rules:
The metadata for chapters and stop frames has the form "chapter: <chapter-no>,<first-frame>-<last-frame>" and stop frames are "stop: <frame-no>". For example:
chapter: 0,1-360 chapter: 1,361-4500 chapter: 2,4501-9450 chapter: 3,9451-18660 chapter: 4,18661-28950 chapter: 5,28951-38340 chapter: 6,38341-39432 stop: 4796 stop: 9089 stop: 9178 stop: 9751 stop: 14818 stop: 14908 stop: 18270 stop: 18360 stop: 18968 stop: 24815 stop: 24903 stop: 28553 stop: 28641 stop: 29258 stop: 34561 stop: 34649 stop: 38095 stop: 38181 stop: 38341 stop: 39127
Note that the emulated Pioneer PX-7 and Pioneer PX-V60 are virtually identical, except that the Pioneer PX-7 has pseudo-stereo for its PSG.
Almost all user preferences can be done via the openMSX console, at openMSX
run time. This is more thoroughly explained in the User's Manual. In short: you can save your
settings with the
save_settings command, which will
save the settings in your personal settings file. The settings file will be
loaded every time openMSX starts.
One of the preferences is the default machine: the machine openMSX uses if
you did not specify one on the command line. The name of this setting is
machines at run time is done via the
machine command (more about this in the User's Manual).
By using the
bind command you can create custom key
bindings. These bindings will also be saved as settings in your settings file
if you issue a
The other settings are discussed in the User's Manual and there is an overview in the Console Command Reference.
If you're a power user and want to specify commands which are executed at
the start of each openMSX start up, put those commands in a text file, one
command per line (i.e. a script) and put it in the
directory. You can also explicitly specify a Tcl file to be loaded and executed
on the openMSX commandline. For this, use the
-script command line
option, which has the filename of the Tcl script as argument.
If you're a power user and want to tweak where openMSX reads and writes files from, you can use these hacky environment variables. Hacky, because we don't really expect anyone to change them. Just in case you really want to, do it at your own risk... Be warned that they may change without notice in a next release.
|The user's home folder, where all data will get stored that openMSX produces.|
|The user's personal
In the section about ROM locations you get an idea about the default values of these on different platforms.
This chapter contains some tips for tuning the performance of openMSX on your system.
The SDLGL-PP renderer needs hardware acceleration to run at a decent speed, with support for OpenGL 2.0. Practically all modern PC hardware has this and that's why we made it the default, but if your hardware doesn't, use the SDL renderer instead.
Getting OpenGL running hardware accelerated used to be a little cumbersome in some situations. However, nowadays there is a big chance that your system already has hardware accelerated OpenGL supported in the default installation of your Xorg or Windows environment. Just make sure you install the development header files for the OpenGL library if you want to compile openMSX with support for it.
You can verify hardware acceleration on your Linux system by typing
glxinfo on the command line. If you have everything working, this command should output a line like this:
direct rendering: Yes.
In any case: if you have a decent video card and you have hardware acceleration working, you can get a lot better performance of openMSX by using the SDLGL-PP renderer.
CPU and graphics performance varies a lot, depending on the openMSX settings and the MSX hardware and software you're emulating. Some things run fine on a 200MHz machine, others are slow on a 2GHz machine.
If openMSX runs slow, you can try the following measures:
set horizontal_stretch 320.
set auto_enable_reverse off
set maxframeskip 10, for example).
scale_factorof 1 with the SDL renderer (75% less pixels to fill compared to the default setting of 2). For most games (and any MSX1 software) it works perfectly, especially when using full screen. The drawback: no special effects at all, not even scanlines. Turning off special effects can also mean a speed up, of course.
This section has some tips specific to the Android version
|Console||openMSX virtual keyboard|
|Joystick button 2||Joystick button 1|
There are two ways to use extra devices in your emulated MSX: you can use a shipped extension (which is analogous to inserting a cartridge with the device into the MSX) or you can modify the hardware configuration file (which is analogous to open the MSX and build in the device). As in the real world, extensions are easier to use, but modifying the machine gives you more possibilities. Normal usage of machines and extensions is covered in the User's Manual; this chapter tells you how you can create or modify these hardware descriptions, which is a topic for advanced users and definitely something very few people will (want to) do. By editing the hardware configuration XML files, you can for example increase the amount of RAM, add a built-in MSX-MUSIC, add a disk drive, create extra cartridge slots etc.
You can modify an MSX machine (e.g. to add devices) by editing its hardware configration XML file. So, let's make a copy of
put it in
It's the config we are going to play with; our custom MSX.
Note: it is convenient to use the user directory (see above)
to store your home-made machines, instead of the openMSX installation directory.
The easiest thing to do is to copy and modify
fragments from other existing configurations that can be found in
share/extensions. For example,
to add an FMPAC to the 8250, just copy it from the
some place in your
mymsx.xml file (between the
<primary slot="2"> <secondary slot="1"> <FMPAC id="PanaSoft SW-M004 FMPAC"> <io base="0x7C" num="2" type="O"/> <mem base="0x4000" size="0x4000"/> <sound> <volume>13000</volume> <balance>-75</balance> </sound> <rom> <sha1>9d789166e3caf28e4742fe933d962e99618c633d</sha1> <filename>roms/fmpac.rom</filename> </rom> <sramname>fmpac.pac</sramname> </FMPAC> </secondary> </primary>
Don't forget to add the
fmpac.rom file to one of your
system_rom file pools.
Because we changed the FMPAC from extension to built-in device, we have to specify in which slot the FMPAC is residing inside the modified 8250. So, we should replace the
slot="any" stuff, with a specified slot as you can see in the above fragment.
The number in the
slot attribute of the
<primary> tag indicates the
primary slot of the emulated MSX you're editing. In this case the second
cartridge slot of the NMS-8250 is used.
<secondary> means sub slot. If we leave it out, the slot is not expanded and the primary slot is used. If we use it like in the above example, it means that slot 1 (of the
<primary> tag) will be an expanded slot. If a
tag has the attribute
external="true", this means that the slot is visible on the outside of the machine and can thus be used for external cartridges like extensions and ROM software.
As explained above, the parameter filename can be adjusted to the name of your (64 kB!) FMPAC ROM
file (note: if the file is not 64 kB (65536 bytes) in size, it won't work).
"balance" defines to what channel the FMPAC's sound will be routed by
default: in this case most of the sound goes to the left channel and a little bit goes to the right channel.
"sramname" specifies the file name for file in which the SRAM contents will be
saved to or loaded from. The saved files are compatible with the files that are
saved by the (real) FMPAC commander's save option.
After saving your config and running openMSX again, you should be able to get
the FMPAC commander with
CALL FMPAC in the emulated MSX!
In a similar fashion, you can also add an MSX-Audio device
<MSX-AUDIO>, note that some programs also need the
MusicModuleMIDI device to
detect the Music Module, an empty SCC cartridge (
etc. Just browse the existing extensions, check the Boosted_MSX2_EN
configuration file and see what you can find.
Devices that contain ROM or RAM will have to be put inside a slot of the MSX,
as is demonstrated with the above mentioned FMPAC example. Other devices don't
Remember that you can not put two devices that have a ROM in the same (sub)slot!
Just use a new free subslot if you need to add such a device and all your
primary slots are full. Devices that do not need a slot, like the MSX-Audio
device, you can add as many as you like.
Another thing you may want to change: the amount of RAM of the MSX: change the
"size" parameter in the
<MemoryMapper> device config.
In principle all of the above mentioned things are also valid for extensions. The main difference is the fact that you should use
"any" for the slot specification as was already mentioned above. Just compare the fragment above with the original FMPAC extension we based it on.
If you understand the basics of XML, you should be able to compose your MSX now!
You can use the ready-made configurations in
Because openMSX is still in heavy development, feedback and bug reports are very welcome!
If you encounter problems, you have several options:
libera.chatand ask your question there. Also reachable via webchat! If you don't get a reply immediately, please stick around for a while, or use one of the other contact options. The majority of the developers lives in time zone GMT+1. You may get no response if you contact them in the middle of the night...
openmsx-usermailing list. If you want to address the openMSX developers directly, post a message to the
openmsx-develmailing list. More info on the openMSX mailing lists, including an archive of old messages, can be found at SourceForge.
For experienced users: if you get a crash,
try to provide a
This will only work if you did not strip the openMSX binary
of its debug symbols.
In any case, try to give as much information as possible when you describe your bug or request.