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RISC OS Versions

A brief history

RISC OS was officially launched in October 1988 as a replacement for Arthur, the first Operating System produced for Acorn Computers' 32-bit ARM powered desktop computers.

Over the next 10 years Acorn steadily updated and refined RISC OS, eventually reaching version 3.71 in 1997. In 1998 Acorn were working on a major new version of RISC OS for their follow-up to the original RiscPC (the new machine was named 'Phoebe' after the character from the US TV series, Friends). Despite the workstations division actually turning a profit, Acorn's other problems at the time led to the closure of the division in September of that year, shortly followed by the breaking up of the company over the next few months.

Ownership of RISC OS since the end of Acorn has been somewhat complicated, but it has basically been owned by Element 14 (part of the former Acorn Group, since swallowed up by Broadcom), followed by Pace Microsystems. It is currently owned by Castle Technology Ltd (manufacturers of the Iyonix PC amongst other things).

Development of the OS continued after Acorn's demise, with RISC OS 4 being released in 1999 by RISCOS Ltd., a company setup expressly to continue the OS. RISCOS Ltd have continued to develop the 26-bit version of RISC OS (which runs on RiscPC, A7000, RiscStation and Microdigital Mico and Omega machines, and also on the Virtual RiscPC emulator) since 1999 under the 'Select' scheme (whereby users pay an annual subscription and receive updated versions of the OS which soft-load over the ROM version). In April 2004 RISCOS Ltd. released the latest ROM-based version of the 26-bit operating system, named RISC OS Adjust. Development continues under the Select subscription scheme.

In November 2002 Castle Technology Ltd. released the Iyonix PC, and along with it the first complete 32-bit version of RISC OS (version 5).

The current situation is that Castle Technology Ltd. own the IP (Intellectual Property) rights to RISC OS, and are developing their 32-bit version. RISCOS Ltd. have a licence to develop the operating system for the market for E-14's traditional desktop computer products, and certain other product areas which have subsequently been agreed. Over time, it is hoped that some of the additional features from RISC OS Select will be added to the 32-bit RISC OS, as the only 26-bit compatible ARM processors still in production are the slower ARM7500 chips.

A list of versions, dates, and companies

The list below is not guaranteed to be 100% accurate or up-to-date, - if you notice any mistakes, please email the webmaster.

RISC OS 2 October 1988 Acorn Computers
A replacement for 'Arthur' (the short-lived operating system supplied with the first Acorn Archimedes machines), RISC OS 2 was supplied on all new Acorn computers until October 1991.
RISC OS 3.00 September 1991 Acorn Computers
Launced with the new 33MHz A5000, RISC OS 3.00 had a fair few bugs in it, which led to the next version being released soon after.
RISC OS 3.10 April 1992 Acorn Computers
Supplied with all new Acorn machines from May 1992, and available as an upgrade for older ones, RISC OS 3.10 fixed a number of the problems from the 3.00 release.
RISC OS 3.11 September 1992 Acorn Computers
Launched with the A4000, A3020 and A3010 machines, RISC OS 3.11 was a minor update to the OS.
RISC OS 3.12 & 3.19 March and June, 1993 Acorn Computers
German language versions of RISC OS 3.
RISC OS 3.5 February 1994 Acorn Computers
The first version of RISC OS to be supplied with the revolutionary 33MHz RiscPC 600, it brough 24-bit colour, higher resolution screen-modes and a revamped desktop. The changes within the OS did unfortunately cause compatibility problems with some older software; upgrades were usually available to fix the issues.
RISC OS 3.6 April 1995 Acorn Computers
Supplied with the 40MHz RiscPC 700, basically a bug fix for 3.5.
RISC OS 3.7 July 1996 Acorn Computers
Launched with the StrongARM processor upgrade for RiscPCs, this allowed machines to use the new 200MHz processor resulting in dramatic speed increases. A number of applications needed to be upgraded in order to work with the new processor and operating system.
RISC OS 3.71 February 1997 Acorn Computers
Supplied with all new StrongARM RiscPCs and the new A7000 series of machines, RISC OS 3.71 was mainly a bug-fix for 3.7.

Support files for the operating systems listed above can be found on RISCOS Ltd's RISC OS 3 support site.

RISC OS 4.00 May 1999 RISCOS Ltd
The first version of RISC OS to be released by RISC OS Ltd. after the demise of Acorn. RISC OS 4 brought a large number of changes to the core workings of the operating system, many originating from the doomed RiscPC2 'Phoebe' project. The new version was faster, more stable and came with a clean new look.
RISC OS 4.02 August 1999 RISCOS Ltd
A bug-fix for RISC OS 4.00, available as an upgrade, or optionally supplied with new RISC PCs and A7000s (which were then being produced by Castle Technology).
RISC OS 4.03 November 1999 RISCOS Ltd.
Towards the end of 1999 several new, 'non-Acorn' RISC OS machines were available, these all ran tailored versions of RISC OS 4.03. (The machines were the RiscStation, Microdigital's Mico and the Kinetic StrongARM upgraded RiscPC from Castle). It also runs on the Microdigital Omega and the Virtual RiscPC emulator.
RISC OS 4.04 January 2001 RISCOS Ltd.
Released for Castle Technology Ltd's 300MHz version of the Kinetic RiscPC.
RISC OS Select 1i9 - 4.29 April 2002 RISCOS Ltd.
The first release version of the Select subscription scheme (developement versions were available to subscribers, but his was the first complete release version). Initially only available for all RiscPC and A7000 machines, later releases worked on RiscStations, Micos, Omegas and Kinetic machines.
RISC OS Select 2i3 - 4.33 October 2002 RISCOS Ltd.
Second release under the Select scheme.
RISC OS 5.00 November 2002 Castle Technology Ltd.
The first fully 32-bit version of RISC OS, released by Castle with their Iyonix PC. It provides some features that are new to the OS, but excludes many of the enhancements from the RISC OS Select scheme. Many older applications (especially games) fail to work on the new XScale processor, however a third-party solution is available, named Aemulor which provides support for many older items of software.
RISC OS 5.01 ? Castle Technology Ltd.
Bug-fix and enhancement release for Iyonix machines.
RISC OS 5.02 February 2003 Castle Technology Ltd.
Bug-fix and enhancement release for Iyonix machines.
RISC OS Select 3i3 - 4.37 August 2003 RISCOS Ltd.
An interim release under the Select scheme, this was never an official, final release, but it was a while before the next version was available.
RISC OS 5.05 February 2004 Castle Technology Ltd.
Bug-fix and enhancement release for Iyonix machines.
RISC OS Select 3i4/RISC OS Adjust 1i2 - 4.39 June 2004 RISCOS Ltd.
RISC OS Adjust is the first 26-bit version of RISC OS to be released in ROM-chip form since 4.04. It is identical to RISC OS Select 3i3, and contains all of the enhancements to date from the Select scheme. It runs on RiscPCs, A7000s, Micos, Omegas, RiscStations, Kinetic RiscPCs and under the Virtual RiscPC emulator.
RISC OS 5.07 September 2004 Castle Technology Ltd.
Enhancements to the USB drivers, nVidia graphics chipset drivers, network software and more for the Iyonix machines.

RISC OS 4 support (including the Select and Adjust releases) can be found at RISCOS Ltd's website. RISC OS 5 is supported by Castle Technology.

More information on RISC OS versions can be found at the following sites:

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