Linux was first developed by Linus on an old .386 system, way back in 1991, and now that cord has been cut, and .386 CPUs are no longer supported: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=743aa456c1834f76982af44e8b71d1a0b2a82e21 From the comments: Pull “Nuke 386-DX/SX support” from Ingo Molnar:  “This tree removes ancient-386-CPUs support and thus zaps quite a bit   of complexity:     24 files changed, 56 insertions(+), 425 deletions(-)   … which complexity has plagued us with extra work whenever we wanted   to change SMP primitives, for years.   Unfortunately there’s a nostalgic cost: your old original 386 DX33   system from early 1991 won’t be able to boot modern Linux kernels   anymore.  Sniff.” I’m not sentimental.  Good riddance. My first ‘home’ Linux system – in 1997 – was an HP Vectra 486 … Continue reading →