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Date:               Fri, 29 Dec 1995 14:54:23 +600 CDT
From:      "Larry Dolinar" <LARRYD@bldg1.croute.com>
To:        questions@freebsd.org
Subject:         Re: more SCSI thrashing-about
Message-ID:  <E0FB09311CB@bldg1.croute.com>

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Thus spake Brian Handy <handy@condor.physics.montana.edu> (Fri, 29 Dec 
1995):

|  Arrgh!  I'm trying to follow this discussion and getting completely shut 
|  down.  Too many part numbers, BIOS names and MB manufacturers have been 
|  bantered about and I've gotten completely lost.
|  
|  I'm also about to put together a couple of systems.  I'm sort of planning 
|  on a P-100 with some sort of SCSI; the onboard NCR was highly recommended 
|  to me as inexpensive and quite sufficient for my needs.
|  
|  Now...Larry just recapped things with the following:
|  
|  >[...]
|  > People constantly say that the best inexpensive PCI SCSI busmastering
|  > cards are those using the NCR 53C810 (or whatever the part number is),
|  > but even there, your're best advised to buy an original NCR card:
|  > Symbios Logic PCI Host Bus Adapter SYM8150S (with BIOS)
|  >                         or         SYM8100S (without BIOS, for MBs
|  >                                                 with the SDMS bios)
|  >[...]
|  
|  These part numbers are lost on me.  I've been trying to get an ASUS MB 
|  *and* get the NCR on-board SCSI.  I've heard arguments about how the BIOS 
|  won't deal with it and I'll have to boot off a floppy, and (sigh) I even 
|  had a dealer tell me I couldn't do it.

If properly implemented, the BIOS _will_ deal with it.  I think the 
confusion stems from the "on-board" terminology.  

If the SCSI card has the controller BIOS on-board, there's an EPROM that
will take care of the SCSI probing at boot-up and enables the card to
attempt booting from whatever lves at the start of the first physical
drive.  Such a card should work in most any PCI motherboard, unless the
motherboard itself has other things that FreeBSD won't like.

The NCR/Symbios 8105S is such a card.  The Adaptec 2940 is another
(usually more expensive) one.


If the card doesn't, but is NCR-compatible, then the motherboard BIOS 
takes responsibility for doing what an EPROM-less (sic) card can't do for 
itself: handle the normal hard drive "ok, let's boot something" sequence.

Particularly important when you've told your setup program that drive 0
is "not installed" (basically required for a SCSI drive as C:).  The
controller chip is still on the card, but the program to run it, isn't.

The ASUS SC200 is such a card.  It may go by different names if in fact 
ASUS doesn't roll their own jelly babies (obscure Python humor).


If the motherboard itself has a SCSI connector, then _all_ the smarts are 
on the system board, and it comes down to whether FreeBSD likes the 
controller chip (it always comes down to that, anyway).  This baby is 
probably somewhat expensive, however.

I think the FreeBSD team started implementations with OEMs that would 
reveal the secrets of their controllers and not bitch about the source 
code being published, which is why the NCR stuff is perhaps further 
along than Adaptec and some of the newer cards.  Only my opinion.

| 
|  At the same time...if I look at the ASUS www page, I see that the 
|  PCI-SC2000 controller comes with the following claim:
|  
|              "Works with ANY ASUS Mb."

As true as anything is, but ASUS seems to shun contact with ordinary 
mortals, just dealers -- their voice mail is the pits.  Or maybe I need 
to change aftershave.

|  
|  Now, I wanted 512KB cache w/ Pipeline burst.  I don't know if that's 
|  somehow the cause of my problems.
|  
|  To wrap things up...can someone explain to me where I'm completely off in
|  left field?  basically, how do I solve this problem and get a nice MB with
|  the cheap SCSI interface? 

Sorry if I've confused things: I just had to answer something to M.Smith
for attributing Michel's comments to me.  But for best performance, 
a supported PCI SCSI card should do busmastering: it cuts down on 
processor overhead, and makes the box that much more responsive.  

AFAIK, the ASUS, NCR, and Adaptec cards all fit this bill (listed in
increasing order of $$ based on US prices).  Others are supported, too.

Other people make SCSI cards based on the NCR chip.  From what 
I've seen on the list, Acculogic and Modular Circuit Technology cards 
also work.  I can dig up the posts of people that claim this if you like.

|  
|  Thanks for your help, and THANKS for your patience.
|  

Not at all -- sorry that I made the thing harder than it should be.  

Something like the ASUS P55TP4 motherboard and SC200 card should do just 
fine.  Add XE to the ASUS board to get an even higher performance model.
My budget doesn't permit this yet (a 486PCI and Symbios card now), but 
I'll probably get the ASUS XE board later.

Corrections welcomed, as always.  And this list is still less 
confrontational than the Novell or Sun groups, as a rule.

hth,
larry



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