The Atari ST Emulator for Unix/X

Welcome to the new homepage of STonX. The new STonX development project is now hosted on SourceForge! SourceForge Logo.


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.


Current features include:

TOS 2.06 runs under the emulator without modification. TOS 1.04 and 1.02 have also been tested with STonX 0.6.7 and work. The other TOS versions (1.6 and >=3.0) are not designed for running on a normal ST and so they will not work with the actual version of STonX at the moment.

System Requirements

These things are required to run STonX: To compile STonX as distributed, you will also need the following:


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. We can only assure you that the latest version will run best on the system most developers use: Linux/i86.

However, people have successfully used STonX on Alpha workstations, 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, we are very interested to fix portability problems, so please reports any unusual happenings to us as soon as possible!


If you have questions or suggestions, there is a STonX development mailing list and a discussion board on the STonX development pages.

If you want to join the development team, you should write a mail to one of the project administrators (see the development pages, too).