RISC OS

Introduction

RISC OS is a computer operating system designed in Cambridge, England by Acorn. First released in 1987, its origins can be traced back to the original team that developed the Arm microprocessor.

Named after the Reduced Instruction Set Computer (RISC) architecture, RISC OS was the first operating system for ARM-based computers.

Introduced on the Archimedes computer in 1987, RISC OS was one of the fastest, most lightweight GUI operating systems ever written, completely stored in ROM and bootable in under two seconds.

RISC OS is not a version of Linux, nor is it in any way related to Windows. It has a number of unique features and aspects to its design.

While Acorn as a hardware manufacturer eventually closed its doors, RISC OS survived through dedicated open-source developer communities. Today, it remains an active, fully functional operating system that enthusiasts still run on modern hardware, including the Raspberry Pi—serving as a living testament to Acorn's brilliant, lightweight software architecture.

Acorn (1978)

Acorn Computers was a legendary British computer company founded in Cambridge in 1978 by Hermann Hauser and Chris Curry. During the 1980s and 1990s, Acorn was frequently called the "British Apple" because it dominated the UK's educational and home computer markets with its innovative hardware and user-friendly software.

The company's journey toward consumer success began in 1979 when Acorn launched the System 1, a kit computer designed primarily for laboratories, universities, and hardware engineers. Building on that foundation, they released the Acorn Atom in 1980, which became their first full consumer microcomputer complete with a built-in keyboard, a TV output connector, and a full BASIC interpreter.

1987: Arthur

Acorn launched the Archimedes personal computer powered by their new ARM2 chip. The system initially shipped with Arthur, a temporary OS written in a rush. Arthur introduced core features like the Iconbar (at the bottom of the screen, pre-dating the Windows Taskbar and macOS Dock) and cooperative multitasking.

1989: Rebranded as RISC OS

Acorn released RISC OS 2, replacing Arthur. It was stored directly on ROM chips, enabling near-instantaneous boot times (often under 2 seconds). It featured dynamic memory allocation, anti-aliased outline fonts, and a fast GUI designed specifically around three-button mouse controls (Select, Menu, and Adjust).

1991–1996: The Golden Era (RISC OS 3)

RISC OS 3 established RISC OS as the dominant computer platform in UK schools and educational institutions. It added vector drawing tools, multitasking enhancements, and sound synthesis capabilities that were years ahead of rival home computers like standard MS-DOS PCs.

Present: Open Source Renaissance

Castle Technology bought the desktop rights and released RISC OS 5 for 32-bit ARM processors (such as the IYONIX PC). In 2006, RISC OS Open Limited (ROOL) was established to manage the source code and port the OS to modern single-board computers like the Raspberry Pi.

RISC OS 5 was re-licensed under the Apache 2.0 open-source license, unifying fragmented intellectual property rights. Today, ROOL actively maintains RISC OS as a lightweight, open-source OS running natively on microcomputers like the Raspberry Pi, BeagleBoard, and Wandboard.

https://www.riscosopen.org/content/downloads/raspberry-pi

Installing RISC OS on the Raspberry Pi How to get started with a BeagleBoard A super quick guide to using RISC OS