RISC iX
| RISC iX running on the Acorn A680 | |
| Developer | Acorn Computers Ltd | 
|---|---|
| Written in | C, ARM assembly | 
| OS family | Unix-like | 
| Working state | Discontinued | 
| Initial release | 1988 | 
| Available in | English | 
| Platforms | Acorn Archimedes | 
| Default user interface | Graphical user interface | 
RISC iX is a discontinued Unix operating system designed to run on a series of workstations based on the Acorn Archimedes microcomputer. Heavily based on 4.3BSD, it was initially completed in 1988, a year after Arthur but before RISC OS. It was introduced in the ARM2-based R140 workstation in 1989, followed up by the ARM3-based R200-series workstations in 1990.