SkyOS is a commercial, proprietary, graphical desktop operating system written for the x86 computer architecture. As of January 30, 2009 development has halted.


SkyOS is the culmination of over ten years of research and development by Robert Szeleney and volunteers.

A young man in University, Szeleney and several friends began the "Sky Operating System" as an experiment in OS design. As the years progressed and the other founding members of SkyOS distanced from the project, Szeleney continued work on the operating system in his spare time.

Szeleney's full-time job was in automation programming, and he already had a fair understanding of operating system design. But he continued to use SkyOS as a learning device, releasing four versions under an open source license.

The project reached the height of its popularity in 2004, when Szeleney decided to close the source of SkyOS and begin work on the fifth version. At the beginning of the year, Szeleney started a paid beta program to fund development and distribution of the OS, expecting to have very few (if any) interested subscribers. At the same time, members of the community hosted a contest to determine the look of the GUI, which drew significant attention to the project. So much attention, in fact, that by the end of that same year, the SkyOS community had tripled in size, and Szeleney had hundreds of active beta testers downloading and testing his twice-monthly releases.

SkyOS underwent many changes after this surge in popularity. Because of significant differences at the source level, Szeleney stopped thinking of what was under development as the fifth version of his operating system, and the name "SkyOS 5.0" was rebranded to simply "SkyOS". A more professional demeanor was taken throughout the project, and Szeleney even considered incorporating under the name "Djinnworks". The SkyOS community has since shrunk significantly from its peak in 2004.

As of 1/30/2009, development on SkyOS is currently halted. The developer is deciding on which course of action to take regarding future development:

  • Open source SkyOS
  • Make SkyOS available for free
  • Specialize on a yet-to-be-defined niche
  • Stop SkyOS development

There is also an experimental attempt to use NetBSD or Linux to solve the driver issues.

Beta releases

Date Released Version
January 11, 2004 Beta 1
February 14, 2004 Beta 3
March 19, 2004 Beta 4
April 9, 2004 Beta 5
May 21, 2004 Beta 6
July 5, 2004 Beta 7
October 1, 2004 to August 6, 2005 Beta 8.x Series
November 27, 2005 Beta 9
March 26, 2006 Build 5550
July 26, 2006 Build 6132
September 3, 2006 Build 6179
November 18, 2006 Build 6669
June 21, 2007 Build 6753
August 4, 2007 Build 6763
October 8, 2007 Build 6796
November 25, 2007 Build 6814
April 1, 2008 Build 6915
August 3, 2008 Build 6947


SkyOS user space lies on top of a custom, modularized, preemptive-multitasking kernel with support for common features like process and thread isolation, memory management/paging, kernel debugging, low-level locking primitives, and real-time PIC/APIC timers. It is a monolithic kernel, with drivers that are dynamically loaded into kernel space via an extension API.

There are some notable features that distinguish the SkyOS kernel from others. These include:

  • Kernel-mode VESA support, allowing for graphical display immediately upon power-up
  • Architecture abstraction layer, allowing SkyOS to be easily ported to other architectures
  • Advanced CPU support, including Multi-Core/SMP/HyperThreading and all the major x86 extensions
  • Full DMA, ATAPI, and ATA/SATA support (with SATA drivers for several major chipsets)
  • Support for popular buses (including USB)

Contrary to a popular misconception, the kernel is not derived from Linux or any of the various BSDs. It was written entirely by Szeleney over the course of several years, and uses no outside code.

Version Processor Memory Hard drive capacity Video card
Required Recommended Required Recommended Required Recommended Required Recommended
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