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RISC OS, the computer operating system developed by Acorn Computers for their ARM-based Acorn Archimedes range, was originally released in 1987 as ', soon followed by ', and '. The next version, ', became ' and was completed and made available in April 1989. ' was released with the very earliest version of the A5000 in 1991 and contained a series of new features. By 1996 RISC OS had been shipped on over 500,000 systems.〔(ART – Acorn RISC OS )〕 ' was released by RISCOS Ltd (ROL) in July 1999, based on the continued development of . ROL had in March 1999 licensed the rights to RISC OS from Element 14 (the renamed Acorn) and eventually from the new owner, Pace Micro Technology. According to the company, over 6,400 copies of on ROM were sold up until production was ceased in mid-2005. ' was launched in May 2001 by ROL. This is a subscription scheme allowing users access to the latest OS updates. These upgrades are released as soft-loadable ROM images, separate to the ROM where the boot OS is stored, and are loaded at boot time. ' was shipped in May 2002, with ' following in November 2002 and the final release of ' in June 2004. ROL released the ROM based the same month, dubbed ' as a play on the RISC OS GUI convention of calling the three mouse buttons 'Select', 'Menu' and 'Adjust'. ROL sold its 500th Adjust ROM in early 2006. ' was released in October 2002 on Castle Technology's ''Acorn clone'' Iyonix PC. is a separate evolution based upon the NCOS work done by Pace for set-top boxes. In October 2006, Castle announced a source sharing license plan for elements of . This Shared Source Initiative (SSI) is managed by RISC OS Open Ltd (ROOL). ' was also announced in October 2006 by ROL. This is the next generation of their stream of the operating system. The first product to be launched under the name was the continuation of the Select scheme, '. A beta-version of , ('), was available in 2007 as a free download to all subscribers to the Select scheme, while in April 2009 the final release of ' was shipped. The latest release of RISC OS from ROL is ', shipped in December 2009. == Arthur == The OS was designed in the United Kingdom by Acorn for the 32-bit ARM based Acorn Archimedes, and released in its first version in 1987, as the Arthur operating system. The first public release of the OS was ''Arthur 1.20'' in June 1987.〔(【引用サイトリンク】 Acorn Archimedes 310 )〕 It was bundled with a desktop graphical user interface (GUI), which mostly comprises assembly language software modules, and the Desktop module itself being written in .〔(Acorn Archimedes )〕 It features a colour-scheme typically described as "technicolour". The graphical desktop runs on top of a command-line driven operating system which owes much to Acorn's earlier MOS operating system for its BBC Micro range of 8-bit microcomputers.〔 Arthur, as originally conceived, was intended to deliver similar functionality to the operating system for the BBC Master series of computers, MOS, as a reaction to the fact that a more advanced operating system research project (ARX) would not be ready in time for the Archimedes.〔 The Arthur project team, led by Paul Fellows, was given just five months to develop it entirely from the ground up—with the directive "just make it like the BBC micro". It was intended as a stop-gap until the operating system which Acorn had under development (ARX) could be completed. However, the latter was delayed time and again, and was eventually dropped when it became apparent that the Arthur development could be extended to have a window manager and full desktop environment. Also, it was small enough to run on the first 512K machines with only a floppy disc, whereas ARX required 4 megabytes and a hard drive. OS development was carried out using a prototype ARM-based system connected to a BBC computer, before moving onto the prototype Acorn Archimedes the A500. Arthur was not a multitasking operating system, but offered support for adding application-level cooperative multitasking. No other version of the operating system was released externally, but internally the development of the desktop and window management continued, with the addition of a cooperative multitasking system, invented by Neil Raine, which used the memory management hardware to swap-out one task, and bring in another between call-and-return from the WIMP-Poll call that applications were obliged to make to get messages under the desktop. This transformed it from a single-application-at-a-time system, to one that could operate a full multi-tasking desktop. This transformation took place at version 1.6 though it was not made public until released, with the name change from Arthur to RISC OS, as version 2.0. Most software made for Arthur 1.2 can be run under RISC OS 2 and later because, underneath the desktop, the original Arthur OS core, API interfaces and modular structures remain as the heart of all versions. (A few titles will not work, however, because they used undocumented features, side effects or in a few cases APIs that became deprecated). In 2011 ''Business Insider'' listed Arthur as one of ten "operating systems that time forgot". 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「History of RISC OS」の詳細全文を読む スポンサード リンク
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