Right, but 20 years ago was 1999. I won’t be surprised to find out many packages won’t work: that CPU doesn’t have SSE2, the RAM limit is 512 MB, and typical systems usually had 64 or 128 MB.

The official page says recommended minimum requirements for Ubuntu 16.04 are 2 GHz dual core processor with 2GB RAM. 20 years old PCs don’t fit.

Yes. But I think it’ll only a matter of time before they stop, too.

> using 64-bit has little value if you have less than 8 Gb of RAM.

Address space brings much value. No need to worry about address space fragmentation, also you can safely use memory mapping, even for large files.

Extra registers also very nice performance-wise, both general purpose r8-r15 and vector xmm8-xmm15.

Finally, when you code AMD64 you can rely on having at least SSE1 and SSE2 SIMD, their support is a requirement.