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Date:      Sat, 31 Oct 1998 20:31:07 -0800
From:      John Polstra <jdp@polstra.com>
To:        dg@root.com
Cc:        Greg Lehey <grog@lemis.com>, hardware@FreeBSD.ORG
Subject:   Re: Mixing 8- and 16-bit shared memory ISA cards 
Message-ID:  <199811010431.UAA24975@austin.polstra.com>
In-Reply-To: Your message of "Sat, 31 Oct 1998 19:55:32 PST." <199811010355.TAA01865@implode.root.com> 

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> It affects all machines with ISA busses, not just early x86. The ed
> driver goes to great pains, however, to attempt to work around this
> problem by putting 16bit cards into 16bit memory mode only while
> actually accessing them.  The rest of the time they are left in 8bit
> mode. So you should be able to mix them in the same 128K region in
> this specific case, but GENERALLY you cannot.

Thanks for the info!  That explains why I didn't see problems when I
"should" have.

Speaking of such matters ... The manual for my SMC 8013 card says that
the card can be put into either an 8-bit or a 16-bit slot.  (It's a
16-bit card.)  But when I tried putting it into an 8-bit slot, and set
flags=0x2 to force 8-bit mode, the probe said something like "failed
to clear shared memory."

John
--
  John Polstra                                               jdp@polstra.com
  John D. Polstra & Co., Inc.                        Seattle, Washington USA
  "Nobody ever went broke underestimating the taste of the American public."
                                                            -- H. L. Mencken

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