This guide will explain how to install RISC OS using the NOOBS Lite (New Out Of Box Software) zip file provided by the Raspberry Pi Foundation on their download’s page. This guide will only explain how to install RISC OS as the ONLY OS on the SD card !!
You will need an SD card formatted to FAT32 and either the NOOBS.zip file or the NOOBS Lite.zip file from the Raspberry Pi downloads page. The process is amazingly simple, once downloaded all you have to do is extract the .zip file onto the SD card using the program of your choice (Linux = 7zip/PeaZip/Ark/etc Windows = WinZip/7-Zip/PeaZip/etc).
Once this is done plug the SD card into the Pi and turn it on, it will start re-sizing partitions and creating new ones, when it is finished you will be left with 3 partitions on your SD card, the normal 2 and an additional recovery partition. You will be greeted by a selection of operating systems to choose from, select RISC OS and click the “Install” button. You will see a warning appear about over-writing all existing data, click “Yes”, it will start installing RISC OS on your system for you, sit back and grab a drink, when it’s done you will see a pop-up notifying you that the OS has been successfully installed, click “OK”.
Your Pi will reboot and you will enter a desktop, it will open up a browser welcoming you to RISC OS and giving you a few useful links which include a guide on how to use RISC OS and one on how to install software. It also tells you a little further down the page how to configure your networking in RISC OS follow the simple steps and reboot and you should be set ! Enjoy exploring RISC OS !