RISC OS
<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.
(2004-09-21)