Subject: Re: optimizations
To: Curt Sampson <>
From: Jonathan Stone <jonathan@DSG.Stanford.EDU>
List: current-users
Date: 09/01/1997 16:07:22
Curt Sampson <> writes:

>>On Sun, 31 Aug 1997, William J. Coldwell wrote:
>> DEC 21x4x Ethernet (or 3Com 905 or derivative)

>Avoid the 3com at this time if you're interested in performance.
>It still uses PIO, not DMA. I believe both the Intel and the DEC
>cards use DMA.

True.  But for the 3c905, that' sa limitation of our driver, not the
hardware. We now have documentation on the 3Com 3c905 DMA, which (as
far as I can tell) does not have the four-byte-alignment restriction
which forces the current DEC cards to use an extra copy.

By the time the `fixed' DEC chips (21143?) come out, a 3c905 driver
might just be faster than the 2114x available now.

And if these machines are going to be on 10Mbit Ethernet (was 21x4x a
typo for 2114x?), it won't make a signficiant difference either way.