RISC OS ( /rɪskoʊˈɛs/) is a series of graphical user interface-based computer operating systems (OSes) designed for ARM architecture systems. It takes its name from the RISC (Reduced Instruction Set Computing) architecture supported. The OS was originally developed by Acorn Computers for use with their 1987 range of Archimedes personal computers using the Acorn RISC Machine processors. It comprises a command-line interface and desktop environment with a windowing system.

From 1988 to 1998, the OS was bundled with nearly every ARM-based Acorn computer model, including the Archimedes range, RiscPC and A7000. A version of the OS (called NCOS) was used in Oracle's Network Computer and compatible systems. After the breakup of Acorn in 1998, development of the OS was forked and separately continued by several companies, including RISCOS Ltd, Pace Micro Technology and Castle Technology. Since 1998 it has been bundled with a number of ARM-based Acorn clone computers such as the Iyonix and A9home. As of 2012^[update], the OS remains forked and is independently developed by RISCOS Ltd and the RISC OS Open community.

Andrew Nicholas James Rawnsley (born 5 January 1962, Leeds) is a British political journalist and broadcaster. A columnist for The Observer, he has written two books on New Labour.

He was educated at the Lawrence Sheriff School in Rugby and later on a scholarship at Rugby School and read History at Sidney Sussex College, Cambridge University, gaining a first-class Honours degree. He was a member of Cambridge University Social Democrats. He was also editor of Stop Press the Cambridge University newspaper of the day, and won the Guardian Student Journalist of the year award in 1984.

Rawnsley began his career at the BBC, working there for two years from 1983, but joined The Guardian in 1985. From 1987 he was the newspaper's parliamentary sketch writer.

In 1993 he moved to The Observer as Chief Political Commentator and Associate Editor, a position he retains. He has won several awards for his journalism, including: British Press Awards Young Journalist of the Year (1987); What The Papers Say Columnist of the Year (2000); Channel 4 Political Awards Book of the Year (2001); Channel 4 Political Awards Journalist of the Year (2003); House Magazine Awards Commentator of the Year (2008).