Meanwhile, in October 2002, Castle Technology released the "Acorn clone" Iyonix PC. This ran a 32-bit (in contrast to 26-bit) variant of RISC OS, named "RISC OS 5". RISC OS 5 is a separate evolution of RISC OS based upon the NCOS work done by Pace. The following year, Castle Technology bought RISC OS from Pace for an undisclosed sum. In October 2006, Castle announced a shared source license plan, managed by RISC OS Open Limited, for elements of "RISC OS 5".