riscos ltd was formed to continue end-user-focused development of risc os after the de-listing of acorn computers following its purchase by morgan stanley dean witter in order to benefit from the shareholding that acorn held in arm ltd in march  riscos ltd obtained exclusive rights to develop and sell risc os  for the desktop market from element  a few weeks later pace purchased acorns cambridge headquarters and staff for £ and then continued to develop its own in-house version of risc os primarily for set-top boxes and other embedded devices