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Date:      Sat, 18 Jan 1997 13:01:43 -0700 (MST)
From:      Terry Lambert <terry@lambert.org>
To:        smp@csn.net (Steve Passe)
Cc:        cbrown@aracnet.com, smp@FreeBSD.ORG
Subject:   Re: Adaptec 3940UW and SMP
Message-ID:  <199701182001.NAA12301@phaeton.artisoft.com>
In-Reply-To: <199701180524.WAA22187@clem.systemsix.com> from "Steve Passe" at Jan 17, 97 10:24:00 pm

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> > Personally, I can't believe that they would design a MB with hardwired
> > interrupts.  You should be
> > able to have a PCI slot without ANY interrupt assigned.  In addition,
> > they all use INTA?  That is
> > kinda a waste.  Sounds like that kinda kludged the interrupt mapping
> > into the system.
> 
> I don't know where this style mapping came from but it seems (in my limited
> knowledge) to be common on MBs these days.  I suppose it was meant to make
> life easier for end users, not having to strap cards for specific INT pins.
> I would think it possible for a card maker to strap both INT[AB] of a bridged
> card to PCI INTA (as an option) allowing the use of only 1 PCI INT line
> in an OS that can handle SHARED INTs, but perhaps there is something about
> the PCI spec that disallows this?

It came from a bridge chpset that was intent on mapping PCI devices
into a predominantly ISA architecture.  The error was in allowing the
architecture to be predominantly ISA to save Intel's market for ISA
multi-I/O and other motherboard chipsets dependent on ISA interfacing,

The correct soloution is to go to internally PCI machines, and if you
want to dip the PCI Vestal Virgin into the Raw Sewage of ISA, you
can bridge ISA to the PCI instead of the other way around.

Just my unbiased opinion, of course.  8-) 8-).


					Regards,
					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.



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