RISC iX

RISC iX was a Unix-like operating system designed to run on the Acorn Archimedes R140, R225 and R260 models. These are fundamentally similar to the A440 (later A440/1) and A540 models. It was based on Berkeley Software Distribution and had a number of innovative features, including a transparent file compression mechanism and a console text copying mechanism more familiar to microcomputer owners than to Unix people.

The R140 had an ARM architecture processor at 8MHz but was hampered by the memory management system, using 32KB pages, and limited swap space on the 47MB (later 53MB) ST506 hard drive. The system was capable of a low-resolution, black and white X-window environment with 4MB RAM.

The R225 came with 4MB RAM (expandable to 16MB), a 26MHz ARM3 and ethernet interface but no hard disk, while the R260 came with 8MB by default, ARM3 plus a SCSI and ethernet interfaces.

There was limited support for other expansion cards and Econet.