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In 1999 RISCOS Ltd acquired a license Element 14 (previously Acorn Computers) to complete development of RISC OS 4 as an upgrade for existing Risc PCs and A7000/A7000+ and for new desktop machines. RISC OS 4 was designed for Phoebe [Risc PC 2] and had been previewed by Acorn to developers as RISC OS 3.80. RISC OS Ltd acquired the latest RISC OS sources with the license. In July 1999 RISCOS Ltd completed development and lauched RISC OS 4 at the Acorn South East Show.
All versions of RISC OS release by RISCOS Ltd have been for 26-bit systems, except for RISC OS 4.42 "Adjust 32" for the Advantage 6 A9Home which is 32-bit. Here is a detailed list of RISC OS Versions .
The initial release of RISC OS 4 was version 4.00 which was an upgrade for Risc PCs and A7000/A7000+. This was only sold at the launch at the Acorn South East Show in July 1999. RISC OS 4.00 was released on 2 ROMs to replace the exisiting RISC OS 3 ROMs and a CD with a new disc image and extras. The major new features of RISC OS 4.00 were:
In addition the kernel was re-written to improve speed and many bugs were fixed. Full details of the RISC OS 4 Features are available from RISCOS Ltd The ROMs used were FlashROMs which allowed RISCOS Ltd to customise each ROM set (e.g. to burn the owners details into the ROM.
RISC OS 4.01 has some minor improvements to the original release. It was also shippped on FlashROMs.
In August 1999 RISC OS Ltd had to suspend shipment of RISC OS 4 due to a worldwide shortage of FlashROM. Shipments resumed in September 1999 using OTP (One Time Programmable) ROMs. The version was changed to version 4.02 reflecting a number of minor improvements. RISC OS 4.02 became the base release for new computer models and the base for future RISC OS upgrades.
There were several versions of RISC OS 4.03, one for the MicoDigital Mico, one for the RiscStation R7500 and one for the Castle Kinetic Risc PC. These versions include changes necessary to support the new hardware.
RISC OS 4.04 was a bug-fix version for Castle 300MHz Kinetic Risc PC.
In February 2004, RISCOS Ltd announced a new version of the RISC OS 4 ROM - version 4.39. The new version included all features developed under the Select Scheme including DHCP support and the ability to boot from CD-ROM. RISC OS 4.39 "Adjust" upgrade was available for Castle Kinetic Risc PC, MicroDigital Omega, Risc PCs and A7000/A7000+ computers. RISC OS 4.39 replaced RISC OS 4.02 as the standard version for new computers when RISC OS 4.02 stocks ran out in June 2005.
In 2005/6 RISC OS converted the RISC OS source code to 32-bit neutrality, the result of this was the release in March 2006 of RISC OS 4.42 for Advantage Six A9Home.
Embedded RISC OS is designed to be used in dedicated devices which do not need to support all components of a desktop system and where the user is unlikely to ever require access to the RISC OS desktop, usually because the device is running a single dedicated application. Acorn's NCOS could be called an embedded system for Set Top Boxes. Typically the customer only wants the OS to support the components his application uses, so the OS should be modular, allowing modules to be selected at build time.
RISC OS Ltd refer to Embedded RISC OS on the back page of a RISC OS promotional brochure .
On 8 February 2002 a RISC OS Ltd Press Release Embedded RISC OS announced the development of Embedded RISC OS for ARM7500 and SA110 devices. It is a componentised version aimed at dedicated hardware applications such as point of sale devices, internet/network terminals, portable data loggers and process contollers. Castle Technology's Neuron system was the first product to use Embedded RISC OS.
On 19 November 2004, RISC OS Foundation Newsletter no 31 , said that Embedded RISC OS had been licensed to Advantage 6. Advantage Six used an embedded version of RISC OS 4.39 in the A75.
I have a development system which is a Simtec EB7500FE with the Embedded RISC OS ROMs, this version of Embedded RISC OS is 4.06 was produced in 2003, . The system starts up in debug mode and then loads a RISC OS desktop. The Task Manager icon is a ROM with a green cog wheel, the About box says "Ally McBeal".
I have no more details of Embedded RISC OS, products using it and its success (or otherwise). If you have more details please let me know.
In May 2001 RISC OS Launched the RISC OS Select subscription scheme to fund further development of RISC OS. The subscription was £105 per year. Subscribers were to get upto 3 CDs per year with new ROM images which could be soft-loaded on top of RISC OS4 and individual modules in both Beta an official releases. In practice releases have been less frequent. The releases up to the end of 2008 are:
| Select version | RISC OS Version | Build date |
| Issue 1 Release 9 | 4.29 | 23-Apr-2002 |
| 2 Issue 3 | 4.33 | 30-Oct-2002 |
| 3 Issue 3 | 4.37 | 11-Aug-2003 |
| 3 issue 4 | 4.39 | 28-Apr-2004 |
| 4 Issue 2 | 6.10 | 20-Apr-2008 |
| 5 Issue 1 | 6.14 | 1-Dec-2008 |
| 5 issue 2 | 6.16 | 19-Apr-2009 |
Full details of the select improvements can be found on the RISCOS Ltd web site, although they are not always easily found.
In 2000 RISCOS Ltd set up The RISCOS Foundation which published a quarterly CD-ROM magazine, Foundation Risc User. The magazine ceased publication in 2007 after the original editor, Richard Hallas left to complete a PhD in the history of Acorn Computers. In 2008 Foundation Risc User was merged with RISCWorld to create Foundation RISCWorld which is published bi-monthly by APDL.