A OS was designed inside England by Acorn for the 32-bit ARM based Acorn Archimedes, and freed inside its 1st version within 1987, as a Arthur operating system.

RISC OS was the rapid development of Arthur Ace.Two fallowing a failure of the ARX project. A number one release was to exist as known as Arthur Deuce, however was renamed to RISC OS Two, & was 1st sold within April 1989. It got co-operative multitasking with some limitations, however was non multithreaded. It used a ADFS filesystem for both diskette & difficult discs. It at the start ran from either the 512 KB ROM module. A WIMP interface offered all the standard features and fixed several of the bugs that had hindered Arthur. It lacked virtual memory and extensive memory protection (applications are protected from either every more, however numerous functions stand to become implemented when 'modules' which keep close at hand fully access to the memory). A independent benefit of the OS was its ROM; it booted super quickly & when it was real life to crash it was impossible to break. Its high performance was due to lot of models existence written inside ARM assembly language. A OS existed witharound modules & these can be updated by modules in RAM as improvements were made. Such is a modularity of RISC OS, that advanced users develop been knhave to swap in their own replacement modules - of these such module gives RISC OS the ability to launder pre-emptive multitasking.

RISC OS Three was freed by using a A5000 within 1991; it was almost fourfold the size of OS Two & ran from either a TwoMB ROM. It improved multitasking & besides set a select few of the additional popular base applications in the ROM. An updated version, Terzetto.One, wwhen discharged late which was sold built-constitutional to the A30x0 system & was available as replacement ROMs for the A5000 & earliest system. RISC OS Three.Phoebe was sold from either 1994 with the foremost Risc PC. After a Risc PC architecture was improved around 1995, the OS was updated to RISC OS Three.Hexad which featured lot better hard disk access and extended networking to include TCP/IP in addition to Acorn's existing proprietary Econet system, although the OS remained inside ROM. Around 1996 the Risc PC was upgraded to a StrongARM processor and a OS kernel was changed to choose benefit, a recently revision existence dubbed RISC OS Three.Septenary.

RISC OS will bring the super intuitive gui, sustaining features like context sensitive menus & permeative drag & drop, & fantabulous consistency through applications thanks to Acorn's elaborated Style Alternative.

Acorn halted operate altogether areas except Set-top boxes in late 1998, and a company was renamed to Element 14 (a Fourteenth element of the periodic table being silicon). RISC OS development was halted in a period of the development of OS Four.Cypher, the beta version, OS Three.Eight, was discharged to developers.

This led to a total of saving efforts, including the creation of the ROX Desktop to provide a RISC OS-such as interface in Unix and Linux systems. 2 similar projects, Impulse & [http://www.acornusers.org/phoenix/posts/forbiddentech.html Eidos's Phoenix], two stalled.

Around 1999 a new company known as RISCOS Limited was founded. It licensed a rights to RISC OS from either a fresh creator, Pace Micro, and continued a development of OS Three.Ogdoad, releasing it when RISC OS Four inside July 1999. RISCOS Ltd's todays version is RISC OS Choose Edition Three (RISC OS Four.39), many thou copies were sold based on data from numbers freed by the babies. A less enhanced Quaternity.03 version is however available at the savings. RISC OS Five occurs as separate evolution of RISC OS Three.Octad from either Castle Technology Ltd for their Iyonix PC line of Acorn-compatibles, which run on the Intel XScale ARM processor. Although the wealth of computer software has nowadays been updated, two or three older applications may single become do in RISC OS Five vithe an ape, since a minor 26-bit ARM CPU function was flushed by Intel from either a XScale. Also, RISC OS Five itself got to exist as ported to do properly on the recently CPU, & abstraction of the graphics & more devices interfaces created, to allow it, e.g., to have standard graphics cards, instead of Acorn's have VIDC chip.

Within July 2003, Castle Technology Ltd bought RISC OS from Pace Micro [http://www.iyonix.com/iyonix/news/riscos.shtml]. RISCOS Ltd & Castle continued maintaining separate development branches of the RISC OS operating models for the select few instance, however following of a drawn-out dispute ended licensing in the period of 2004 them keep around agreed to merge the two competing streams, lakes, and wells throughout.

More information
[http://www.riscos.com/ RISCOS Ltd] [http://productsdb.riscos.com/admin/riscos.htm What is RISC OS?] [http://www.castle-technology.co.uk/ Castle Technology Ltd] [http://www.drobe.co.uk/ Drobe Launchpad - RISC OS News and Information] [http://www.iconbar.com/ The Icon Bar - RISC OS News, Information, and Forums] [http://www.riscos.info/ RISC OS Programming Information] [http://www.filebase.org.uk/ ANS Filebase - RISC OS software database] [http://www.riscos.org/ RISCOS.org] [http://arcem.sourceforge.net/ ArcEm - Open Source Acorn Archimedes emulator capable of running RISC OS. Available for Linux, Microsoft Windows, Mackintosh &, oddly, RISC OS] [http://www.redsquirrel.fsnet.co.uk/redsquirrel.html Red Squirrel - Free Microsoft Windows RISC OS emulator] [http://www.osnews.com/story.php?news_id=6170 Emulating RISC OS under Windows]

de:RISC OS fr:RISC OS nl:RISC OS