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'''SymbOS''' is a free multitasking operating system for Z80 based 8-bit computer systems written by [[Prodatron|Prodatron]]. At present it is available for the computers of the Amstrad CPC as well as for all MSX models starting from the MSX2 standard and all Amstrad [[PCW|PCW]] (Joyce) models until the PcW10. Contrary to early 8-bit operating systems it is based on a microkernel, which provides pre-emptive and priority oriented multitasking and manages RAM memory with a size of up to 1024 kB. SymbOS contains a MS-Windows like GUI, supports hard discs with a capacity of up to 128 GB and can already be booted on an unexpanded Amstrad CPC-6128, [[PCW|PCW]] or a 128K-MSX2.

== History ==

Therefore, the CPC's own OS (in combination with AmsDOS) and [[CP/M|CP/M]] were the only two known OSes for the series, but the question remained: since most CPCs have 128K (most C64 only have 64K), a screen-resolution of 320x200 with 4 colours (C64 only has 2 colours for each 8x8 area in 320x200) and some more advantages, why not have something similar? So the SymbOS-Project was born. SymbOS stands for "SYmbiosis Multitasking Based Operating System". SymbOS is a demonstration of what has been achieved on the CPC: real preemptive multitasking, dynamic memory-management for up to 1024K and a totaly MS-Windows-like GUI are the three most important features.

=== Events ===

*''08/2007'': SymbOS release 2.0 is out

== Technical background ==

While the MOS Technology 6502 can not move the stack, the Z80 can freely replace it to any position in the memory, which is more or less a condition for pre-emptive multitasking. The existance of an alternative register set accelerates the content switching between the tasks dramatically. The restriction of Z80 systems to a 64 kB address space can be solved with bank switching. In this way computers like the Amstrad CPC and PCW, MSX, Enterprise or SAM Coupé are able to access hundred or thousand of kilobytes of memory.

== Feature overview ==

**Number of different process priorities: 9

**Maximum number of timers: 32

*'''System manager'''

**Maximum number of applications: 24

*'''Desktop manager'''

**Maximum number of windows: 32

**Maximum number of controls per window: 1000

*'''File manager'''

**Maximum hard disc size: 128 GB

**Maximum file size: 2 GB

**Maximum number of devices: 8

*'''Source code'''

**Source code size (OS Release 2): ~ 44.000 lines (1,3MB)

**Source code size (Applications): ~ 48.000 lines (2,0MB)

*'''Supported platforms'''

**Amstrad [[CPC|CPC]]-6128 (unexpanded) and compatibles ([[CPC TREX|CPC TREX]], [[C-ONE|C-ONE]])

**MSX2 with 128KB Ram (unexpanded) and compatibles (MSX2+, MSX TurboR, OCM)

*'''Supported external hardware'''

**[[Dk'tronics|dk'tronics]] memory expansion 64K-512K and compatibles ([[Dobbertin|Dobbertin]], [[SYMBiFACE II|SYMBiFACE II]])

=== Messaging ===

== Graphical user interface ==

The complete content of a window is defined with "controls". These are e.g. slider, check boxes, text lines, buttons or graphics. The background or not visible areas of a window don't need to be saved in a bit-map buffer. If an area is restored on the display, its content will just be redrawed. Because of this the SymbOS GUI works much more memory-friendlier than most other 8-bit GUIs.

== File system management ==

SymbOS supports the file systems CP/M, AMSDOS, FAT12, FAT16 and FAT32 on all platforms. With the last one SymbOS is able to address mass storage devices with a capacity of up to 128 GB. Also the ability to administer files with a size of up to 2 GB is uncommon for an 8-bit system. Because of the FAT support data exchange with other computers is quite easy, as most 32 and 64 bit operating systems do support the three FAT file systems.

== Applications ==

**[[SymShell|SymShell]] (command line interface)

=== SymStudio ===

[[SymStudio|SymStudio]] is a Windows-based IDE (integrated development environment) by [[Trebmint|Trebmint]] for SymbOS similiar to MS Visual Studio. SymStudio makes it possible to develop SymbOS applications in Assembler or Basic ("SymBasic"). It is also possible to convert PC graphics and videos into the SymbOS format ([[Format:SGX (SymbOS graphic files)|SGX]], [[Format:VID (SymbOS video files)|VID]]). Have a look at [[SymStudio|its article]] for more information. Currently there is only a beta version available.

== Porting and cross platform ability ==

By keeping a basic condition for an operating system, the strict separation of hardware and application software by the supply of an intermediate layer, SymbOS applications run platform-independently on each computer and do not have to be adapted for a special system. Exceptions are applications, which access directly the hardware.

== Motivation ==

SymbOS was originally started as an experiment to find out, how far it is possible to implement a multitasking based operating system with a windows GUI on an 8-bit computer of 1985. Also GEOS contributed to the motivation, but the structure and features of SymbOS aren't similiar to this system. The release in 2006 proved, that such a "mini windows" is possible on a 20 years old home computer only with quantitative limitations. SymbOS is one of the largest retro computing software projects of the last years. One of the goals of the project is to copy in combination with various hardware extensions a complete PC job.

== Web links ==

*[http://cpcrulez.free.fr/applications_symbos_apply_preview.htm french information on CPCRulez]

*[http://www.wacci.org.uk/magazine/137/137_03.html "New Generation - CPC Windows?"] ([[WACCI|WACCI]] article by [[ChaRleyTroniC|ChaRleyTroniC]])

*[http://www.msx.org/forumtopicl6203.html Main thread on MSX.org]

*[http://video.google.com/videoplay?docid=-6071242217428356949&q=symbos SymbOS presentation(Video) at RetroEuskal 2006]

[[Category:SymbOS]] [[Category:Operating_System]] [[Category:CPC_GUI]]