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Date:      Mon, 1 May 1995 23:35:54 +0200
From:      se@MI.Uni-Koeln.DE (Stefan Esser)
To:        Paul Richards <paul@isl.cf.ac.uk>
Cc:        current@FreeBSD.org
Subject:   Re: NCR 53C700
Message-ID:  <199505012135.AA18437@FileServ1.MI.Uni-Koeln.DE>
In-Reply-To: Paul Richards <paul@isl.cf.ac.uk> "NCR 53C700" (May  1, 20:26)

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On May 1, 20:26, Paul Richards wrote:
} Subject: NCR 53C700

} Does anyone know anything about these SCSI controllers. I just tried to
} install FreeBSD on one and it didn't recognise it. Are they similar to the
} NCR cards we currently support or is it a totally different beast.

The NCR 53c8xx chips used on PCI SCSI cards are 
the integrated PCI bus versions of the 53c7xx.

The 8xx offer a few additional features over the
older 7xx, but the most important difference is,
that the 8xx offer a standard configuration mode
for interrupts, DMA and addressing of registers 
on the chip.

The 8xx controllers offer better performance, but
this doesn't mean, that support for the 7xx would
be of no use ...

On the other hand, there is only one motherboard
that comes with oboard 53c700 chips (sold by 
Siemens/Nixdorf). I know of no add on cards with
that chip, and of no other system that has it
on the motherboard.

} Anyone planning to get it working?

It wouldn't be to hard to modify the NCR 53c8xx 
driver for the 7xx. This would require patches
to the program loop executed by the NCR (all the
"interrupt on the fly" commands must be replaced 
by standard interrupt commands, for example).

I'm not sure about the DMA engine or need of an
external DMA controller, but I can check the 
details in a 53c7xx data book.

But I don't have the hardware, and I don't think
many others have, so I currently don't intend to 
put any effort in support for the 7xx. (What kind
of machine do you have this controller in ?) 

Trying to write a driver without physical access to 
a machine to run it on would be a silly idea, IMHO :)


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
 Weyertal 80
 50931 Koeln



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