I can't say where, but there is still a RISC OS based real-time radar processing and target tracking system running, providing live data feeds for safety critic

I can't say where, but there is still a RISC OS based real-time radar processing and target tracking system running, providing live data feeds for safety critical systems. It was a joy to program, but it got killed (in my industry) because customers had been screwed over by vendors locking them into specific hardware, then raising prices once the customer had no way out. So the contracts always specified COTS hardware ... "Commercial Off-the-Shelf". This was always, always interpreted as meaning PC hardware. We transitioned because we had to, but the lamented the loss of the elegant, simple, clean designs we could use on RISC OS. I still do.