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Re: USB Host-Host cables

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On Tue, Jun 19, 2018 at 09:11:43AM -0400, rhkramer@gmail.com wrote:
> On Tuesday, June 19, 2018 08:02:11 AM Richard Hector wrote:
> > On 19/06/18 23:47, rhkramer@gmail.com wrote:
> > > On Monday, June 18, 2018 11:27:55 PM Stefan Monnier wrote:
> > >> So I think your cable is much less "Serial" than you think.
> > > 
> > > Just because I'm tired of seeing this thread (even though I make an often
> > > feeble attempt to ignore it), I will mention that Ethernet is serial ;-)
> > > (full duplex in many cases)
> > 
> > Ah, but is it still?
> > 
> > Gigabit (1000base-T) uses all 4 pairs simultaneously, and also encodes
> > multiple bits per symbol, which I think makes it effectively parallel.
> Well, I'm not familiar with gigabit Ethernet.  But even using all 4 pairs 
> simultaneously means that it might be some combination of serial and parallel 
> (I mean, 4 pairs isn't sufficient to carry 8 bits in parallel).

Parallel doesn't necessarily mean 8 bit. And 100BaseT sends three voltage
levels over the differential pair, so it's a tad more than 1.5 bits per
"wire". But then, it's 4B5B (because it has to weave in the clock) so
it's a tad less. 1 gigabit uses more pairs, but I guess each one is used
serially (because of clock skew), so it's more like "a bundle of serial",
and uses a more complex modulation (PAM), so it's more bits/baud even.

I think the "classical" distinction serial/parallel breaks down a bit

- -- t
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