Also found in: Acronyms, Wikipedia.


(operating system)
(Reduced Instruction Set Computer Operating System) The operating system originally developed by Acorn Computers for their Archimedes family of personal computers.

RISC OS replaced the Arthur operating system used on the first Archimedeses.

It is written in ARM assembly code and distributed on ROM so it takes up no disk space and takes no time to load. It supports cooperative multitasking with memory management and includes a graphical user interface or "WIMP". It is written in a highly modular style and makes extensive use of vectors so it is easy to modify and extend by loading new modules in RAM. Many system calls (called "SWIs" - software interrupts) are available to application programmers and some of these are available as user comands via a built-in command-line interpreter. RISC OS also supported outline fonts when only bitmap fonts were available on most other platforms.

Following the virtual demise of Acorn, development of RISC OS 4 was taken over by RISCOS Ltd on 1999-03-05 and released on 1999-07-01.

Latest version: 4.39, as of 2004-09-21.
References in periodicals archive ?
RISC OS was developed in the 1980s, before Microsoft had achieved quite the level of global dominance that it now enjoys.
A Windows-based terminal includes: an embedded operating system such as DOS, Windows CE or any real-time operating system such as EPOC32, RISC OS, etc.
Operating systems supporting ARM include Accelerated Technology Nucleus PLUS, Acorn RISC OS, Eden OS, Etnoteam EOS, ISI pSOS, JavaSoft JavaOS, Lucent Technologies Inferno, Microsoft Windows CE, Microware OS-9, Motorola Memos, Perihelion Helios, Psion EPOC/32 and Wind River Tornado.
NASDAQ:CRTM) announced today that the Company's forthcoming line of uniView(TM) interactive television products will utilize the Acorn RISC OS operating system and worldwide web browser technology as well as an Advanced RISC Machines (ARM) microprocessor.