RISCOS Limited - Definition and Overview

RISCOS Ltd was a UK limited company created in 1999 to continue user-focused development of the RISC OS operating system after the collapse of Acorn. RISCOS Ltd obtained exclusive rights to develop and sell RISC OS 4 for the desktop market from its new owners, Pace Micro Technologies PLC, who themselves continued to develop their own, in-house version of RISC OS primarily for set-top boxes and othe embedded devices.

RISCOS Ltd completed work on RISC OS 4 in mid-1999 and it was released as an upgrade for existing machines. Work then continued on a system of soft-loaded operating systems, released under a rolling scheme named 'RISC OS Select'.

In July 2003, Castle Technology Ltd bought all rights to RISC OS from Pace Micro Technologies. They then released a modified version of Pace's 32-bit RISC OS as RISC OS 5 for their Iyonix PC. The result was a long-running and acrimonious dispute between RISCOS Ltd and Castle over licensing which ultimately lead to Castle termintating RISCOS Ltd's license to develop, sell and sub-license RISC OS 4. An end to the dispute was signalled when RISCOS Ltd and Castle agreed to being work on merging their development streams and re-unify RISC OS, with Castle's engineers working on key system functionality and RISCOS Ltd on user-facing elements. As a result, RISCOS Ltd was renamed RISC OS Developments Ltd.