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Skyos logo.svg
developer Robert Szeleney et al. a.
License (s) proprietary
First publ. December 15, 1997
Current  version 5.0 Build 6947 (August 3, 2008)
Kernel monolithic
ancestry SkyOS (no ancestors)
Architecture (s) x86
Languages) Multilingual
(including English , German )

SkyOS ( Sky O perating S ystem ) is a currently not maintained operating system for x86 - PCs , which was largely developed alone by the Austrian Robert Szeleney. It started as an open source hobby project, was meanwhile available free of charge as closed source software and should be placed as a commercial operating system with version 5. From 2003, paid beta versions appeared , linked with the promise that buyers would later receive the stable, productive version free of charge as soon as it was released. However, this stage has not been reached. In January 2009, Szeleney stated that the further development of the software had been "temporarily stopped". The latest beta version, Build 6947 from 2008, has been publicly available since August 2013.


Robert Szeleney originally started the development of SkyOS in 1996 as a pure bootloader . The first version (0.1) of the 16-bit operating system, initially written in assembler , appeared on December 15, 1997. Version 2 was started in 1998 and now represented a 32-bit system written in C. Up to version 3, which was completely rewritten again SkyOS was open source. The online magazine OSNews named SkyOS Best Hobby OS in 2003 . Version 4 was free, but closed source. Version 5 was supposed to be commercial, but didn't get beyond a paid beta tester program.

It turned out to be difficult for the small development team to keep up with current technical developments and to provide drivers for new hardware, for example. Development was therefore officially paused in January 2009. Szelesney said he was experimenting with replacing his own, monolithic SkyOS kernel with the Linux kernel or NetBSD's . Finally, he told that he was looking for other ways to continue SkyOS development.


SkyOS was designed primarily for the desktop area, and tried to position itself between Windows and Linux , with the main goal of easy use of the graphical user interface . Although it had a largely POSIX- compatible programming interface , it did not see itself as a Unix derivative , as it otherwise had no similarities with Unix . With SkyOS, for example, the graphical user interface SkyGI , unlike in Unix, was an integral part of the system, similar to Windows. The reason for this was the easier handling of the system by the user.



The hardware support remained very incomplete in many places, so technologies such as WLAN or Bluetooth were not supported. In contrast, it was possible to operate printers, CD burners, ACPI and various USB devices such as mass storage devices and input devices. Although most graphics chips were supported by Nvidia , ATI and Intel , the drivers did not offer support for the 3D functions.

Desktop concept

With SkyOS, the taskbar is located at the top center and changes its size depending on the number of open programs. The desktop only contains links to programs and files, not files themselves. SkyOS does not use any workspaces - programs are switched via the taskbar or the keyboard combination Alt + Tab. Programs can be started using a dock- like program called Subnecto . A special feature are the system-wide mouse gestures , with which practically the entire system can be controlled.


SkyOS had a Linux emulation layer and was therefore able to run Linux applications. But there was also software that was written natively for SkyOS. Most programs are ports of free software from other operating systems, mostly from the Unix world:

Most of the existing programs were included with the standard installation; additional applications could be installed free of charge using an update tool called the Software Store .


Playing audio and video files in SkyOS was taken over by the Integrated Streaming System ( ISS ), which enabled programmers to implement playing an MP3 file with a single line of code. The MediaCenter , the standard application for playing videos and audio files, could also play DVDs . In addition to the MediaCenter, there was also a port for the VLC media player . There was also a proof of concept for a SkyOS MediaStation, an application similar to Windows Media Center .

More services

In addition to the Integrated Streaming System, around 20 other services were working in the background and could be activated via the SystemManager . Particularly noteworthy is the index feeder , which created a constantly updated search index. The File and Folder Sharing service also started and configured a Samba server, the Webserver service an HTTP server , the Gesture Executor enabled system-wide mouse gestures, and the Weather Service downloaded current weather data for a location and displayed it in the SkyOS taskbar .


The 64-bit journaling file system SkyFS was based on OpenBFS, Haiku's file system and a reimplementation of the Be File System . It is a 64- bit - journaling file system and supported indexable metadata , which can significantly speed up the search for specific files. It was also able to manage drives with a size of up to 64 zettabytes . The maximum file name length was 255 characters. Although SkyFS was no longer compatible with BFS due to the numerous changes, SkyOS still offered support for mounting BFS partitions and other file systems, such as FAT32 .


The BranchFS is a virtual file system and fulfills a number of different tasks:

  • After you have burned a file system, you can switch back to the burned file status at any time.
  • It enables files to be created or changed virtually on read-only file systems, e.g. ISO 9660 (CDs) - the changes are saved on the hard disk.
  • SkyFS attributes can be written on other file systems and also searched and created by the IndexFeeder .


As an operating system that is mainly intended for desktop use, the SkyOS team tried to localize large parts of the operating system. The basis for this was a cross-system localization system. The most important parts, for example the installation, have been translated into around 30 languages, including German.


Similar to Ubuntu , the system was booted live from the CD during installation. The desktop started like a live CD , all programs were available. If you wanted an installation, you clicked on an icon on the desktop, the installation program was started. The system including all programs was still available during the installation.

Advantages and disadvantages

Supporters of the operating system appreciated the high speed with which programs are executed and the simplicity of the system, which is mainly achieved by a single, central settings program.

Critics criticized the limited hardware support and the conditions of the beta test program, in which the testers pay for their work and in return receive the stable version later, which however never appeared. Since the code was closed, there has often been speculation about possible violations of the GPL and other free licenses, since it is considered unlikely that an individual with comparatively little support could develop such a complex system.

See also

Web links

Individual evidence

  1. Robert Szeleney: SkyOS development is currently halted ( Memento of the original from November 10, 2016 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. , January 30, 2009. @1@ 2Template: Webachiv / IABot /
  2. Thom Holwerda on SkyOS chasing butterflies , January 30, 2009.
  3. Robert Szeleney: SkyOS Public Beta - Latest SkyOS Beta now publicly available! ( Memento of the original from November 10, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , August 9, 2013. @1@ 2Template: Webachiv / IABot /
  4. Eugenia Loli-Queru: OSNews 2003 Awards - Our Favorites This Year ,, December 31, 2003.
  5. Robert Szeleney: The Experiment ( Memento of the original from March 13, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , June 8, 2009. @1@ 2Template: Webachiv / IABot /
  6. Thom Holwerda: Szeleney: "SkyOS Is Not Dead" ,, March 2, 2010.
  7. Gunder123: SkyOS Now Runs Linux Binaries Natively , Slashdot , October 18, 2001.