Subject: Re: BNC/AUI support for alpha UDB.
To: Ross Harvey <>
From: Chris G Demetriou <>
List: port-alpha
Date: 01/13/1997 20:12:22
> Avalon has ALL the dec ethernet chip manuals. Our netbsd project won't
> start for another month or so, but I would be happy to provide information
> to someone working on things now.

Unfortunately, this won't help the BNC problem on the UDB.

from what i've gathered:
	(1) the selection of BNC/AUI or TP is done by an on-chip
	    register, but

	(2) (at least on the multia) the selection of BNC or AUI
	    (once you've selected the BNC/AUI setting on the chip)
	    is done via a multia-specific register that's somewhere
	    in the Multia's motherboard register spaces (i.e. _not_
	    in the 21040's PCI configuraton, I/O, or memory space).

The right databook to have in this situation is a multia technical
reference manual.  The 21x4x databooks may be peripherally useful, but
won't help solve the problem at hand.

> Note also that these chips are in widespread general's not
> just an alpha issue.

As far as I'm aware, the Multia BNC issues Really Are specific to the
implementation of the built-in ethernet on the Multia, and have no
significance to the rest of the world.

At least for some boards (e.d. the DE500, or whichever has AUI, BNC,
and TP), media selection works quite nicely.