Re: EMC compatible computers

[Jon Elson <elson-at-pico-systems.com>]

Dave Lantz wrote:

>my math puts it at (aprox) 1/2 the par-port speed (ECP=2MB/sec)
>
Well, that is for DMA transfers, IF the reciving device can possibly 
handle it that fast.
My work with non-compliant EPP/ECP motherboard chips indicates nobody 
can run at
that rate, because some chips send the strobe BEFORE the data!  The rest 
of them send the
strobe at the same instant as the data.  So, the slave device has to 
artificially delay acknowledging
a command to allow for the data on the cable to settle.  Practical 
operation at about 800 nS
per byte transferred is possible, though.  So, the ethernet beats it on 
raw speed, but the protocol
overhead with ethernet probably at least evens up the score.

Jon