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Date: Thu, 14 Aug 1997 18:52:28 -0500 (CDT)
From: "Daniel M. Eischen" <deischen@iworks.InterWorks.org>
To: gradz@inlandnet.com, questions@FreeBSD.ORG
Subject: Re: Adaptec AHA-2910B
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> I won't take too much of your time. Is the Adaptec AHA-2910B SCSI
> adapter supported? The Adaptec page says it uses the same "technology"
> as the 2940 but doesn't go beyond that except to say that it does not
> have a BIOS so it can not be booted.

If what Adaptec says is true, then it should, or could be made to,
work.  Be leary though when they say 2940 compatibility.  They'll
probably mean it is a 785x or 786x (786x is found on the 2940AU)
based controller.  These controllers only have room for 3 commands
at a time on the controller, whereas the 2940UW and the vanilla
(non Ultra) 2940[W] have storage for 16 commands on the controller.

The FreeBSD driver supports paging SCBs (these commands) in and out
of the controllers storage area, so it can achieve better performance
(paging is supported for all 78xx chip sets).

If you performance is an issue, consider the 2940UW.  If not, the 2910B
should be fine (as long as it is a supported chipset).

The NCR controllers are well supported under FreeBSD and also cost
much less than the Adaptec controllers.

Dan Eischen
deischen@iworks.InterWorks.org