Linux now runs on the Commodore 64, the 1982 8-bit home computer, thanks to some incredible work by Onno Kortmann: "But does it run Linux? can now be finally and affirmatively answered for the Commodore C64!" The 64 stands for "64 kilobytes of RAM" and its brain was a MOS 6510 clocked at 1 MHz. Linux takes 39 hours to boot on it.
Thanks to emulaThor on Youtube, @hpingel on github, a real C-64 has now successfully booted for the first time. Congratulations, so you are likely the first person on the planet to have ever booted Linux on a real C-64! :-) …
The C-64 took about 150 billion 6510 cycles with ~8bits of activity each cycle to get to this point, so the bit error rate of the system needs to be <<1e-12 to not have any bit flips anywhere. Which is probably not very easy given the old hardware and the long runtimes. So … the title of "First person successfully booting Linux on a C-64 and entering a shell without any crashes" is still up for the taking :D
Practical modern operating systems have been developed for 8-bits, such as 64os for the Commodore 64 and SymbOS for the Amstrad CPC/MSX.