Exploring RISC OS on the Raspberry Pi

Lead Image © Kanlayavadee Thephasdin na Ayuthaya, 123RF.com


Linux is great, but if you didn't want to experiment with new things, you wouldn't be hacking on a Raspberry Pi. Sometimes new things are old things: The venerable and much-loved RISC OS, which is older than Linux and was specifically designed to run on the ARM chipset, is finding a new audience with the rise of the Pi.

RISC OS was the first operating system made for the ARM processor. Both ARM and RISC OS were developed in the 1980s in Great Britain by Acorn Computers. At the time, Acorn enjoyed huge popularity in Great Britain and was frequently referred to as "England's Apple." Older readers will probably remember the BBC Micro that was based on MOS-6502 and that, starting in 1981, ran the legendary BBC Basic programming language. By 1987, RISC OS had become the operating system for the likewise legendary Acorn Archimedes with its 32-bit ARM CPU. In 1993, RISC OS shipped with the RISC PC and in 1995, on Acorn's A7000.

In their time, these early RISC computers were equipped with amazing technology, and they were extremely fast. However, they were not exactly inexpensive. For instance, the price of the Acorn Archimedes would be around 5800 Euro (nearly US$ 8000) in today's currency.

With the rise of Windows and Intel, RISC OS lost favor with the PC crowd, but it has continued to evolve out of the limelight as a specialized system that is fast, simple, and well suited to the peculiarities of ARM hardware. Now RISC OS is gaining a new following as an operating system option for the Raspberry Pi.

The fact that the Raspberry Pi uses an SD card for file storage makes it easy to experiment with different operating systems. You can keep as many SD cards as you like, and use a different operating system for every purpose – or even for every mood.

If you're experimenting with finding the perfect system for your Pi, you'll eventually bump into RISC OS. Although RISC OS has a much smaller user base than Linux – and it supports fewer third-party applications, many users say it runs faster on a low-end system like the Raspberry Pi. And, if you're into simplicity, you might just find that RISC OS has everything you need.

Changing Times

In the 1990s, Acorn embarked upon an important collaboration with Apple and VLSI ARM Ltd, leading to a series of products, such as the legendary PDA Newton from Apple as well as the Acorn's RISC PC. Over the intervening years, Acorn went after new markets and concentrated on media set-top boxes and network computers that were based on RISC OS. However, success eluded the company.

Acorn dissolved its development department in 1998. That same year, a group of Acorn dealers and developers founded a new company called RISCOS Ltd [1] to take over the license for further development of the operating system. ARM, which, in contrast to Acorn, was enjoying significant success, also gained its own independent holding company in 1998.

In 1999, Acorn Computers took the name Element 14 Ltd. [2] and attempted to position itself in the marketplace of DSP-based solutions. The set top box division and RISC OS were sold to Pace Micro Technology [3]. At this point, the development for RISC OS diverged along two different pathways; one followed by Pace Technologies and the other by RISCOS Ltd. The licenses for the manufacture of the RISC PC were taken over by Castle Technology, and the remainder of Element 14 landed finally in the possession of the chip manufacturer Broadcom.

Starting in 2002, Castle Technology [4] assumed most of the work for continuing development of RISC OS-based computers. At first, Castle licensed the RISC OS from Pace, but then Castle bought the system outright in 2003. In 2006, Castle had the newly founded RISCOS Ltd start the process of disclosing source code for RISC OS. For the first time, it therefore became possible to port RISC OS to newly developed ARM hardware like BeagleBoard, PandaBoard, and, starting in 2012 to the Raspberry Pi.

The number of users and developers of RISC OS shrank with time, in part because of the two different paths of development. Luckily only one system has been active since 2013 – the RISCOS Ltd system, or ROOL as it is known. The current version is RISC OS 5.

A hard core of users and developers, primarily located in Great Britain, still work doggedly on the future of RISC OS. They meet regularly at events, exchange information, and introduce new products. When the system was ported to the Raspberry Pi, they began to hope that RISC OS would once again become more widely used. As a result, ROOL has made it a goal to make the platform accessible to a broader group. The company has also undertaken to improve the integration with the Pi hardware.

RISC OS is available under a "shared source" license. The dual-license scheme used for RISC OS lets you use or modify the system for non-commercial purposes. See the RISC Open OS Shared Source FAQ for more information [5].

Modular Structure

RISC OS is a slim operating system with a modular structure. Consequently, it is ideally suited for use on less powerful hardware devices like the Raspberry Pi. RISC OS was conceived as a one-user system and supports cooperative multi-tasking by means of its window manager WIMP, which is aptly named after "Windows, Icons, Menu, Pointer."

One of the inherent characteristics of RISC OS is that it offers a large number of small tools and applications. These tools include an editor, pixel- and vector-based drawing programs, and a music program. Additionally, RISC OS provides BBC Basic, and thus delivers a very fast Basic Interpreter, which has been used to create quite a few of the tools and applications of the operating system.

Moreover, the Raspberry Pi distribution of RISC OS contains additional applications, including a PDF reader, the NetSurf web browser, the packet manger PackMan, and lots of documentation, such as programming books and a version of the excellent book Acorn Reference Programming Manual (RPM), which is more than 1,000 pages long.

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