*BSD News Article 44179


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From: se@MI.Uni-Koeln.DE (Stefan Esser)
Newsgroups: comp.os.386bsd.questions,comp.unix.bsd.freebsd.misc
Subject: Re: External cache prevents booting? (was: FreeBSD 2.0 Boot Floppy
Date: 18 May 1995 11:07:55 GMT
Organization: Institute for Mathematics, University of Cologne, Germany
Lines: 31
Message-ID: <3pf9qb$6jr@news.rrz.uni-koeln.de>
References: <3lvemo$eu8@kiwi.cssc-syd.tansu.com.au> <3n6f4p$4rr@klaava.helsinki.fi> <3o3ijd$3p6@park.uvsc.edu> <3o4l27$arn@nntp1.u.washington.edu> <3o8fj1$aas@helena.MT.net> <3pcsf8$toq@jeeves.niehs.nih.gov>
NNTP-Posting-Host: fileserv1.mi.uni-koeln.de

In article <3pcsf8$toq@jeeves.niehs.nih.gov>, duling@niehs.nih.gov (Dave Duling) writes:
|> >That's a big suprise to me considering that the 53cx7XX series of chips
|> >don't do bus-mastering.  And, I'm *positive* that the NCR 53cx810
|> >controller I installed wasn't doing bus-mastering even though it worked
|> >under DOS.  The reason I know is because it wouldn't work correctly
|> >under OS/2 and FreeBSD because of a buggy BIOS which caused it to never
|> >responds to interrupts.
|> >
|> >However, it was pretty darn fast considering it was running in PIO mode.
|> >The author of the FreeBSD driver showed me a way to run the card in PIO mode
|> >under FreeBSD, and I was getting 2.4MB/sec out of the drive.
|> >
|> 
|> Hey, no fair.  Could you pass this information on to the rest of us.

What for ?

Running  the NCR 53c8xx controllers as PIO mode devices would 
be a really silly thing to do. They get over 8MB/s in DMA mode
out of a single modern FAST SCSI drive.

The PIO mode of this chip is only useful for testing purposes.


Regards, STefan
-- 
 Stefan Esser				Internet:	<se@ZPR.Uni-Koeln.DE>
 Zentrum fuer Paralleles Rechnen	Tel:		+49 221 4706017
 Universitaet zu Koeln			FAX:		+49 221 4705160
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 50931 Koeln