Vim

Andy Wingate maintains the RISC OS port of Vim.

Vim runs as a GUI task, as an ANSI task with Nettle, and will also work out of the desktop as well. It requires ZapFonts and ZapRedraw, and an OS that can handle more than 77 files per directory. (raFS or RISC OS 4+ and an E+ format disk will address this requirement.) While untested on RISC OS versions prior to RISC OS 4 it should work OK, but machines with limited memory may have problems.