Raspbian

What is Raspbian?

Raspbian is an unofficial port of Debian Wheezy ARMHF, developed by Mike Thompson and Peter Green. Its compilation settings were optimized to utilize hardware floating-point math ("hard float" ABI), making it fully compatible with and tailored for the Raspberry Pi.

The initial build was released on July 15, 2012.

Why was this port necessary?

The official Debian Wheezy ARMHF release required ARMv7-A CPUs or higher, whereas the original Raspberry Pi ran on an older ARMv6 architecture.

Prior to Raspbian, the Debian Squeeze image provided by the Raspberry Pi Foundation was based on Debian ARMEL. This legacy port used software floating-point emulation ("soft float" ABI) designed for less capable ARM devices. As a result, it failed to leverage the Pi’s actual floating-point hardware and ARMv6 instruction set, significantly bottlenecking performance in floating-point intensive applications.

Final Release & Legacy

The last official release under the name Raspbian was issued in February 2020, after which it was officially rebranded as Raspberry Pi OS.