The Atari ST Emulator for Unix/X

Current release version: 0.6.5

Current pre-release version: 0.6.7-epsilon

Please go to the SourceForge Home of STonX to discuss the further development of STonX!

This page last updated on Mon May 25 1998

Written by Marinos Yannikos and Martin D. Griffiths
with many contributions from Internet Citizen.


Description , Status , System Requirements , Speed , Portability , Availability , Alpha (pre-release, sort of) versions , Inofficial STonX homepage , Bugs , Documentation , STonX update mailing list , Contributors , Related Projects and Useful Links , What's New


STonX is an Atari ST Emulator intended primarily for use with Unix and the X Window System. Ports to MS-DOS and Microsoft Windows 95 have been released by other people or are being worked on. STonX is distributed under the GNU License, meaning that source code is available as well - and, of course, it's free software.

Here are the screenshots published in Atari World: color (showing GRAV2) and monochrome (using the Xlib-VDI driver) modes.

Here is a new screenshot (64KB .gif) showing the colour VDI mode (800x608x16) with STonX running on an Alpha clone with a Sun IPC as X display. The values are "real" timings, since the Timer C is running at 200Hz (as it has done since STonX 0.5.3 or so).

This is how fast STonX runs on a 366MHz 21164 based Alpha workstation running Red Hat Linux 4.1. Note, that this is not even a particularly high-end system, since a major german PC distributor is going to sell 500MHz 21164 based Alphas for approx. 6000DM soon.

Current features include:

TOS 2.06 runs under the emulator without modification. TOS 1.4 has also been tested with STonX 0.5a and works. 1.0 and 1.2 work with limitations. TOS 2.05 has been tested and works with STonX 0.5.3.

Features that have been implemented but not yet released:

Stuff on the schedule:


STonX seems to work reasonably well for many people, although a few annoying limitations and problems remain. Some of them are:

System Requirements

These things are required to run STonX: To compile STonX as distributed, you will also need the following: If you want to patch STonX or help me with something, you'll also need the following things:


STonX will run faster than a 8MHz ST on a DX4-100 most of the time. On my P5/133, GEMBench reports 693% CPU speed relative to an Atari ST, but that result is heavily distorted by the fact that integer divisions are not common in typical programs but have a strong effect on the GEMBench result. A better (IMHO) benchmark is the bench1.prg which comes with STonX. It reports approx. 3.3 times ST speed for my system, which sounds more reasonable. Note that all the benchmark results for STonX measure only the process time used by STonX itself, not e.g. for the X server which slows down the visible speed of emulation but runs as a separate process.

Due to the nature of the emulation, big-endian CPUs will run STonX faster than little-endian ones, and x86 CPUs are generally better supported (with some inline assembly). The graphics speed of "clean" GEM programs can be increased dramatically by using the Xlib-VDI driver (-vdi option), since the VDI graphics functions will then be performed directly by the X server (instead of the emulated TOS VDI).


Different versions of STonX have been tested on different systems, but it's difficult to keep track of where it runs or doesn't run without access to many different systems. I can only assure you that the latest version will run best on my system (Linux PC), second best on other systems available to me (Alpha workstations with Digital Unix and Linux, most likely).

However, people have successfully used STonX on Silicon Graphics workstations, HP PA-RISC systems, RS/6000 with AIX, proprietary systems by Siemens, PCs with FreeBSD, Suns with Solaris and SunOS and others.

As you can imagine, I'm very interested to fix portability problems, so please reports any unusual happenings to me as soon as possible!


The STonX archive contains binaries for several systems, as well as source code. This archive was inaccessible for some time because my good old SPARC died and I had to copy it from a backup I kept.

You will also need a TOS image, but I cannot provide this for FTP since it is copyrighted by Atari Corp. PLEASE! do not ask me for TOS images!

STonX is also available on some versions of the german S.u.S.E. Linux distribution (STonX version 0.6.5 as of May 1997).

Inofficial STonX homepage maintained by Tony Smolar

Tony Smolar has offered to maintain an "inofficial" STonX homepage at and a STonX FAQ. He also has a compatibility list for software running with STonX.

Alpha/pre-release versions

I'll be putting snapshots of versions under development in
this place, so that you can see what's happening. These versions will be broken most of the time, sometimes they may even fail to compile. Don't despair; if you think you can fix portability problems with these versions, let me know. For other problems, please wait until a new "release" is made available, which should be more usable.

As of pre-release version 0.6.7-delta, I recommend using this instead of the "release" versions; it is more stable, bug-free (several emulation bugs are gone again!) but not tested enough to replace 0.6.5 completely.


There are still quite a few of them. Some of the more annoying ones are: Most other problems are due to missing features. The warnings about missing or unknown keysyms can be eliminated by fixing the "Keysyms" file to work with your display.

A better maintained list of open issues, things that need to be fixed etc. can be found on the STonX TODO List page.


Not much available yet, sorry! Some day, I might write something useful, but I'd rather work on the code instead...

There's some information in this place now, with more being added whenever I feel like it.

A discussion forum using HyperNews has been set up at It is still in testing stage and the connection is slow, so please be careful with it. If this works, it may become a very useful source of information about STonX.

STonX update mailing list

I've set up a mailing list for minor version number update notifications (major updates are posted to and comp.emulators.misc). To be added to this list, just send
me an e-mail message stating that you wish to be added.


The following people are some of those who contributed to the STonX project (random order):
Tony Smolar -- Maintainer of the FAQ and the inofficial STonX homepage
Hans Groenewold -- Program testing and new keyboard code
Juergen Lock -- Bug fixes and FreeBSD patches
Bernd Paysan -- Xlib-VDI patches
Hansjoerg Opperman -- NeXT testing and bug fixes
Richard Jelinek -- Many useful suggestions
Frank Naumann - Many bug reports
Michael Hohmuth -- Suggestions, Bug fixes
Michael Ritzert -- Contributed code, testing and fixes
Gard Eggesboe Abrahamsen -- Early testing over the Net
Ofir Gal -- Author of GEMBench (useful for debugging and benchmarking)
Des Herriot -- Author of xzx, helped me with sigaction()
Uwe Seimet -- Helpful suggestions, early testing
(and several other people I forgot or neglected ;-))

Thanks! Without you, STonX would be much further from where it should be by now! :-)

Related Projects

This section lists a few projects related to STonX and/or Atari, 68K etc. emulation.

Some useful links:

What's New

Mon May 25 1998

Old News...

Marinos "nino" Yannikos,