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Date:      Mon, 27 May 96  1:30:16 +0000
From:      Andrew.Gordon@net-tel.co.uk
To:        freebsd-scsi@freebsd.org, j@uriah.heep.sax.de
Cc:        "(FreeBSD hackers)" <freebsd-hackers@freebsd.org>
Subject:   Re(2): SCSI hostadapter
Message-ID:  <"1443-960527013356-2539*/G=Andrew/S=Gordon/O=NET-TEL Computer Systems Ltd/PRMD=NET-TEL/ADMD=Gold 400/C=GB/"@MHS>
In-Reply-To: <199605240641.IAA21885@uriah.heep.sax.de>

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> Reminds me: does anybody have any information about the 53C400?
> 
> I've got a couple of these boards sitting on a shelf, they used to
> accompany HP ScanJets.  I don't think they will be anything that can
> be called performant, but just out of curiosity...  Perhaps they are
> good enough to recommend them to someone who needs an adapter for an
> Archive Viper 150 or so (which i'd recommend rather than those floppy
> tape crap).

As it happens, I was trying to put a system together yesterday, using mostly old junk I had lying around.  Since I didn't care about disc performance, and I had an old SCSI drive plus a 53C400 adapter handy, I thought I would use those (booting off floppy with some suitably hacked bootblocks).

The adapter originally came with a scanner, (but not an HP one) and contains just the 53C400 plus an LS245 buffering the databus and some SCSI termination resnets.  Curiously, the nca driver probes the card as a NCR-5380 despite the fact that the chip on the card is clearly labelled as a 53C400A.  However, hacking the driver to probe only for 53C400 (it normally probes 5380 first) caused the card not to be detected at all.

This particular card does not support interrupts (it doesn't even have any fingers on the connector for any of the IRQ lines).

For the hard drive, it seems to work reliably, but is _very_ slow - here are some bonnie results (and results for the same motherboard/drive but with a 2940 instead, for comparison):

         -------Sequential Output-------- ---Sequential Input-- --Random--   
         -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---   
      MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU   
ncr   16   105 89.0   110 10.8    55  1.3   109  8.4   111  5.5   9.6  8.7   
2940  16   560 28.4   553  7.7   266  6.5   612 28.7   605  8.3  24.8  3.8   

(the drive is an old SCSI-1 device, async transfers only.  CPU is AMD 486/100).


Results with a tape drive added were mixed.  A couple of times, it got into a state where the SCSI bus was jammed, giving "st0: timed out", and total disaster if the hard drive was on the same controller.  With just the tape drive, it worked OK, but I was not able to get it to stream with a DC6525 tape (normal data rate around 200K/sec).  With a DC6150 (data rate about 90K/sec) it performed normally.



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