Comment by lxgr
4 years ago
128b/132b is the more efficient coding. The closer to 1 the fraction is, the less coding overhead it has, and 128/132 is larger than 8/10.
4 years ago
128b/132b is the more efficient coding. The closer to 1 the fraction is, the less coding overhead it has, and 128/132 is larger than 8/10.
Actually, I just noticed that 128/132 is the same fraction as 66/64 so both scheme has the same encoding efficiency. So USB-4 did no "revert in terms of efficiency.
Indeed, according to the wiki page the subtetly is:
> USB 3.1 and DisplayPort 2.0 use 128b/132b encoding, which is identical to 64b/66b, but duplicates each of the preamble bits to reduce the risk of undetected errors there.
I guess that was found not to matter so they went back to the more normal 64/66 in USB4? I'm really weak on the hardware stuff so I really have no idea.