This article is from the comp.sys.acorn FAQ, by Paul Vigay with numerous contributions by others.
N.B. The RiscBSD name has been dropped entirely in favour of NetBSD/arm32.
Due to the rapid development of NetBSD exact details about the latest incarnation of it are not kept in this FAQ. This is a port of NetBSD, a Unix variant, to the RiscPC. However for the latest information you might like to consult these web pages, listen to the NetBSD email list or email the people involved with development of it:-
NetBSD/arm32 - For RiscPC and later machines - http://www.netbsd.org/Ports/arm32/
NetBSD/arm26 - For Archimedes and other pre arm600 boxes - http://www.netbsd.org/Ports/acorn26/