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To: Mark Hittinger <bugs@ns1.win.net>
Subject: Re: VLB Disk Controllers 
Cc: hackers@FreeBSD.ORG
In-reply-to: Your message of Sat, 07 Oct 1995 16:30:28 EDT
Date: Sat, 07 Oct 1995 17:53:18 -0600
From: Warner Losh <imp@village.org>
Sender: owner-hackers@FreeBSD.ORG
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: I have had problems with vlb cards running above 33 MHZ.  The effect appears
: like the loss of interrupts or extreme interrupt latency.  I have seen this
: especially bad on amd 486dx2/80 (vlb clk 40mhz) and 486dx2/100 (vlb clk 50mhz).
: I suspect the problem would exist on 486dx50 as well.

The VLB spec doesn't go above 33MHz for two or more cards.  It goes,
I'm told, to 50MHz for one card, but I've also heard that the 33MHz
limit is hard, so I don't know what to believe.  Either way, it isn't
surprizing that you've had problems with one i na 40MHz or 50MHz
system, since you'll likely have a video card on that bus as well.

I've had no problems with my VLB UltraStor 34F and either a no name
ET4000 card, or an S3 #9 Lvl 11 at 33MHz.

Warner