Subject: Re: 2940 controllers integrated on the motherboard
To: Andrew Reilly <>
From: Justin T. Gibbs <>
List: current-users
Date: 04/14/1996 07:59:43
>I can't comment on the PCI-bridge issue, but there was certainly a problem
>with the AIC7850 (2940-ish) controller and the NetBSD aic7xxx driver.
>Fortunately, Justin Gibbs (author of the aic7xxx driver) has just made
>it work for the 7850, so I have high hopes that my IWILL-P54TS motherboard
>based system will soon be running a version of BSD.  That will probably be
>FreeBSD at first, because that's where the new driver will probably show up
>first.  I'll let you know how I get on.  (The 2940 controller cards actually
>have an AIC7870 controller, which has 16 SCBs.  The 7850 only has 4, aparently

The IWILL-P54TS is known to work now with the FreeBSD driver.  The 7850
only has 3 SCBs.  The aic7770 has 4, the aic7870/7880 has 16.  Some 
3rd party designs may use the memory port on the aic7870/7880 to offer
255 SCBs.  I also have work in progress that will allow 255 concurrent
commands on all parts except the aic7770 <= Rev C that uses SCB paging.

>As soon as I'm running, I'll post some benchmarks, to see how that affects
>performance.  Since this is a personal workstation, I don't really need
>killer NNTP server level performance.  I can say, though, that even under
>windows the disk performance feels better than I remember the Sun boxes at Uni
>having...(without numbers though, this impression is completely

The 7850 is just as fast as the aic7870/7880 part except when you have
multiple drives in your system or are using a high number of tags per
device since the low number of SCBs kills performance.

>The IWILL mob (Taiwanese motherboard manufacturers) also do versions called
>P54TSW and P54TSW2 that have the relevant AIC- SCSI-Wide and Ultra controllers
>on them.  Can't comment on how well they work, though.

These are known to work also.

>Good luck,

Justin T. Gibbs
  FreeBSD: Turning PCs into workstations