These days Raspberry Pi OS (formerly Raspbian) is the standard OS for Pis. But it wasn’t quite always this way. In the very beginning Pidora, an experimental Fedora spin, was the leading effort, while Raspbian started off as a couple of hobbyists doing a mass rebuild of Debian. Things soon changed, and once “hard float” support was added to Raspbian (enabling it to use the Pi’s floating point unit for a nifty speed boost) in 2012 it rapidly became a de facto standard. The following year the project was adopted by the Raspberry Pi Foundation, who hitherto had left the software side of things to the community.
Several other OSes appeared in the early Pi days, Xbox Media Center) and a port of the unofficial Arch Linux for ARM devices. These generally built off distros’ existing support for the ARMv6 architecture. As time went on new, more powerful Pis appeared although, to be frank, it took a fair old while until OSes appeared that could take advantage of the newer hardware. The Pi 3, introduced in 2016 was the first device to feature a 64-bit processor, but it wasn’t until this year that 64-bit OSes for it became widely available.
