[rescue] FDDI card

[Dave McGuire]

On February 24, Scott Newell wrote:
> >Ah, come on now....  you want that they should have tried too run two
> >different carrier frequencies over the bloody coax now or something?
> 
> I'm kinda stupid when it comes to ethernet, so please don't come down to
> hard on my ramblings here...
> 
> As I understand it, the base in 10Base-5, 10Base-2, or 10Base-T refers to
> baseband, i.e., no modulated carrier, as opposed to broadband.

  Ethernet is a manchester-encoded bit stream, which effectively
results in a 10MHz overall bit transition rate.

> Forget that, and continue on with the idea of multiple carriers
> frequencies.  How do you run multiple machines on shared media?  Each
> machine on the shared pipe will have to talk on a different frequency, and
> listen on _all_ the other frequencies at the same time.  You've also got to
> assign each machine their transmit and receive frequencies.  Of course,
> this assumes shared media.

  This sort of frequency-division multiplexing would require bandpass
filters for each of the receivers, though.  This would push
manufacturing costs way up, and certainly couldn't be easily
retrofitted into existing stuff.  Many of 100baseT (or
100base[whatever] for that matter) stem from the fact that 10Mbit
ethernet wasn't designed with future speed increases in mind.

     -Dave

-- 
Dave McGuire
St. Petersburg, FL         "Less talk.  More synthohol." --Lt. Worf