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Date:      Wed, 23 Aug 1995 17:49:07 +0200
From:      se@zpr.uni-koeln.de (Stefan Esser)
To:        Jim Lowe <james@miller.cs.uwm.edu>
Cc:        current@freebsd.org
Subject:   Re: Matrox Meteor Video Capture Card Driver
Message-ID:  <199508231549.AA18689@Sysiphos>
In-Reply-To: Jim Lowe <james@miller.cs.uwm.edu> "Re: Matrox Meteor Video Capture Card Driver" (Aug 23, 10:37)

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On Aug 23, 10:37, Jim Lowe wrote:
} Subject: Re: Matrox Meteor Video Capture Card Driver
} > From: "Rodney W. Grimes" <rgrimes@gndrsh.aac.dev.com>

} I tried lowering the PCI latency timer from 80 to 40, then to 20, then 1,
} then 0.  It helped me get a few frames at 640x480 before the machine
} hung.  I also tried disabling the cpu to pci burst mode.

It takes some 10 cycles to arbitrate for the PCI bus
and to send the first data word. Numbers less than 
10 (decimal) are not too useful for this reason.

Is there any error message or other fault indication
than the system freezing ?

} I have been running the meteor in a machine with and adaptec controller
} for 5 days and it never hung.  I am still not sure why the machine
} hangs with the ncr controller.

I take it the Adaptec above is an 2940 ?

Could you please try having "ncrconsole -v -p 1" 
run in another window. Watch the "pre" and "post"
times, which account for the time to initiate a 
transfer and to retrieve the SCSI status.

The lower limits for these numbers are the NCR and 
disk drive SCSI overhead. The command overhead of
the NCR depends on its instruction execution rate
(usually in the low MIPS range).

Do you have a NCR 53c815 or 825 to compare the 810 
results with ? 

One of the differences between the 8x0 and 8x5 is
the reading of instructions in burst mode, which 
might help.


-- 
 Stefan Esser, Zentrum fuer Paralleles Rechnen		Tel:	+49 221 4706021
 Universitaet zu Koeln, Weyertal 80, 50931 Koeln	FAX:	+49 221 4705160
 ==============================================================================
 http://www.zpr.uni-koeln.de/staff/esser/esser.html	  <se@ZPR.Uni-Koeln.DE>



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