Introduction and overview

SkyOS is an operating system written from scratch for x86 PC's. As required for a modern operating system, it supports features such as multiprocessor support (SMP), virtual memory, memory protection, multitasking and threading etc. Additionally, SkyOS has a built-in GUI system named SkyGI. All features of the OS will be explained later in detail.

Graphical user interface

The graphical user interface of SkyOS (SkyGI) is very flexible and powerful. Full theming and skinning is supported as well as really nice graphical features like:
- Alpha blending
- Transparent windows and alpha blended windows
- Window shadows
- Rounded windows
- Free form window shapes
- Window animations
- Optional OpenGL rendered windows
- Antialiased truetype fonts with font kerning
- Support for BMP, GIF, JPG, PNG and ICO out of the box
- Various themes like WindUI, Classic, Revolution and BeOS
- Supports Windows (tm) .RES resource files in seperate files or embedded in applications
- Supports application translation to any language
- Widgets: Button, Checkbox, ClientWindow, ColorSelectDialog, ComplexEdit, Dialog, Dynamic bitmap, Edit field, FileSelectDialog, FileView, FontSelectDialog, GroupBox, Frame, ListView, Menu, MessageBox, Popup, ProgressBar, PromptDialog, PropertyPage, PropertySheet, Scrollbar, Slider, Static text, StatusBar, TextEdit, Title, TreeView and ToolTip.
- and many more
- Hardware acceleration for various graphic cards like ATI, NVidia, Chips&Techs,...

Filesystem

The native filesystem used in SkyOS is SkyFS. This 64-bit journaled filesystem supports modern features like attributes, indexes, and queries. To access other operating systems' native filesystems, SkyOS comes with FAT12/16/32, BFS (BeOS), Ext2/Ext3 and ISO9660 (CD-ROM) filesystem drivers.

Internationalization, localization and translation

The entire SkyOS GUI and core system supports UTF8. From the time you press a key on the keyboad (UTF8) to the final step (rendering UNICODE TrueType characters), all text and characters are handled in UTF8. Because of this, you can type and view text in any language like english, german or even chinese.
A built-in translation system makes it possible to translate applications very easily to other languages. Language switching works on the fly. This means, right after you changed the language settings, all applications are switched to this language.
The primary language for the SkyOS GUI and native applications is english. Out of the box, the GUI and most applications have a german translation too.
The GUI and a few appliations are available in german, english, dutch, swedish and polish already.

Networking

An entire TCP/IP Stack is available for SkyOS. This TCP/IP Stack implementes all required protocols on each layer like Ethernet, IP, ARP, ICMP, UDP, TCP and a Berkley compatible socket interface.

Multimedia

With SkyOS you can watch your favourite videos and DVD's as well as listening to Audio CD's and MP3's.

ISS (Integrated sound system)

The ISS is a very well integrated sound system which makes it very easy to access the audio multimedia services of SkyOS, though providing a very powerful interface. The simplest way to play an audio file in an application is by just calling the ISS_PlayAudioFile function with a filename.

On the other side you can create really complex audio applications by using the various functions provided by ISS.
For example you can create two audio streams, one stereo, one 5.1 DolbyDigital, connecting an echo filter to the second, associating the 5.1 stream with a SB Audigy live and the stereo stream with a basic stereo soundcard and apply various software digital filters to individual streams.

Feature of the ISS:
- Supports unlimited number of simultaneous playing audio streams
- Automatic down / upsampling
- Automatic stream mixing
- Streams can be sent to different soundcards or can be "broadcasted" to all soundcards
- Use various digital filter (volume, effects, sampling,... ) for audio streams
- User can set volume for each audio stream seperatly using the mixer
- Builtin extandeable plugin system to automatically decode various sound file formats like MP3, Wav, Vorbis, WMV,..
- Requires very low CPU usage by using the recent implemented fast DataExchange interface
- ISS configuration is done by a plugin for the system manager, the central configuration interface to SkyOS
- Requires zero configuration for basic audio output

Internet

SkyOS comes with two WebBrowsers, SkyKruzer - a KHTML port and Links. Using this browsers you can easily browse the internet and download files.

Available software

SkyOS comes with native applications as well as ports of well known software.
The most popular available software for SkyOS might be:
- AbiWord
- GIMP
- GTK
- SkyKruzer (KHTML based WebBrowser)
- GNU Compiler collection
- Bochs
- Perl
- SDL
- Quake I/II
- VideoLan
- SkyDeveloperStudio
- ...

User-friendly

One of the most important goals for SkyOS is to be user friendly. This means a consistant GUI for all applications as well as an easy to use and navigate desktop. For example, all system settings an user can modify are accessibly through one application, the system manager. Everything you can configure or tweak, is done with it.
Also, SkyOS comes with a nice and easy to use installer for installing SkyOS the first time.

Hardware support

Besides the really broad support for graphic chipsets, SkyOS has drivers for various other hardware like network cards, sound cards and a fully working USB1.1 Stack with support for USB mass storage devices, Hubs, Mouse, Keyboard and Printers.
As input devices you may use any mouse (PS/2, serial or USB) or an Elo or Guenze Touchscreen.

A few more technical features and details

Multitasking and multithreading

The SkyOS kernel itself is a full preemtive multitasking kernel. This means the there is no global kernel lock. The Scheduler is a "abstract virtual object" which uses SchedulerClasses to perform the actual scheduling.
The first SchedulerClass "realtime" is a priority based, round robin scheduler. Alternativly you may use the "quantum" scheduler which isn't as restrictive as the realtime scheduler when switching tasks.

Virtual memory and memory protection

SkyOS makes use of paging and segmenting from 80386+ processors. This means, that each task is memory protected against other tasks, and more important, the kernel is protected against user programs. So normally, no user program can crash other tasks or the kernel itself. Each task can access up to 3GB of memory. (Limitation is given of free disk space only).

Extendable, modular system core

The SkyOS kernel is full runtime extendable. This means that you can compile a kernel with ~70KB only which is able to load all required modules (filesystems, drivers, network,...) on demand. Module loading is handled by the module manager (which loads the module when it's really needed) or implicit by the user via system commands.

Image Manager

The SkyOS Image manager is responsible for loading binary images
Following binary images are supported in version 3.7.7:

COFF I386
AOUT I386
ELF I386
PE I386
PE-DLLs ( Dynamic link libraries)

SkyOS supports dynamic link libraries. (DLL's). These DLL's are loaded automatically by the image manager when they are needed

Resource Manager

The resource manager is a very important main part of SkyOS. Whenever you normally use a list or a tree to store runtime data, this is done with the resource manager in SkyOS. This resource manager is a very flexible hash indexed tree which stores almost all runtime data of SkyOS. For example, all opened files, opened windows, installed drivers, open network connections, font cache,... almost eveything is stored in this tree. A special node, the "registry node" get serialized to disk too. Using this node SkyOS implements a "system only" registry like windows. Furthermore, each application can have it's own registry which is accessible through the resource manager. The main advantage of using the resource manager is that it provides a easy and common way to retrieve and store any kind of data (binary, value, text, ...) in a very fast way.

Things you may know

First released SkyOS version was v0.1 released on 15th, Decemeber 1997. (Features: 16bit real mode, simple (very, very simple) gui, no user tasks).

The creator, and lead-developer of the Sky Operating System is Robert Szeleney (Chief Software Architect). Other developers and contributers include Kelly Rush (Head of Operations), Chris Marshall (Lead Software Developer), and Alex Forster (Lead Graphics Designer).