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From: dsmall@well.UUCP (David Small)
Newsgroups: comp.sys.atari.st
Subject: Re: Seagate 296N, 277N
Message-ID: <14930@well.UUCP>
Date: 12 Dec 89 08:13:42 GMT
References: <8912061949.AA01045@NARNIA.SAIC.COM>
Reply-To: dsmall@well.UUCP (David Small)
Organization: Whole Earth 'Lectronic Link, Sausalito, CA
Lines: 33


The basenote discusses the 277N drives and interleaves.

	Steve, I have both the 277R and 277N; the 277R runs with an OMTI 3527
controller, that I recommend without reservation, at 1:1.

	As you may know, the Spectre v.1.51 had a problem with the 277N.
File copies to the 277N, when the drive was formatted at 1:1, would sometimes
fail. We *finally* tracked it down to the Seagate onboard controller board.
The board was not capable of accepting SCSI commands immediately after
transferring data; a delay was needed. This is the first drive we'd seen that
required this delay, out of many. (And heck, maybe *we* are the ones out of
SCSI spec).

	My 277N worked fine under TOS at 1:1 interleave, so my guess is that
Atari is using different I/O code with a delay, or the natural overhead of
GEMDOS is adding sufficient delay. It doesn't take much to make the 277N
start working with 1:1 -- just turning on Spectre's disk monitor will do it.

	I've been told repeatedly that Seagate has done many different
revisions of the controller ROM, some to try to fix this problem, by 
manufacturers who buy the Seagate products in quantity. (It drives them up
the wall, too.) Hence, my 277N experience may not apply to you, so you know.

	Nowadays, we recommend "Slow SCSI" or 1:2 format on Seagate 277N, 296N,
and 157N drives. I think possibly the 4096 80 mb unit wanted it, but
can't recall. 

	Hope this helps some.

	-- thanks, Dave / Gadgets

	(!hplabs!boulder.edu!tcr!gadgets!dsmall)