ARX

ARX was a Xerox-like operating system developed by Acorn computers in the UK and at the Acorn Research Centre (ARC) at Palo Alto for their new ARM RISC processorss. It was a pre-emptive multitasking, multithreading, multi-user operating system. It was not finished in time to be fitted to the Archimedes range of computers, which shipped in 1987 with the Arthur operating system, which was later superseded by RISC OS.

The Acorn Research Centre was later bought out by Olivetti.