ARX (operating system)

ARX was an unreleased, Mach-like operating system that Acorn Computers developed at its Acorn Research Centre in Palo Alto for the ARM based Archimedes personal computers, with development continuing under Olivetti after it acquired Acorn, though the project was cancelled before release. It was written in Modula-2+, used a microkernel, Unix-like design, and supported preemptive multitasking, multithreading and multiple users, presenting a graphical interface through dedicated keyboard keys. To fit inside a 512 kilobyte ROM it ran much of the operating system in user mode, and it included a window system, a toolkit, a UI editor and a text editor built around Interscript. Because ARX was never finished, the Archimedes computers shipped in 1987 with Arthur, later renamed RISC OS, which descended from Acorn's earlier MOS operating system instead. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/