The Free On-line Dictionary of Computing (30 December 2018):

RISCiX

    /risk-icks/ (Or "RISC iX") BSD-based
   Unix developed by Acorn Computers Ltd. (Cambridge, UK) to
   run on 32-bit ARM RISC processors.

   RISCiX was launched circa 1989 for three production machines -
   the R140, R260, the discless R225; and other prototypes.

   (2003-09-24)