RISC OS definition 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.