Path: utzoo!attcan!uunet!lll-winken!ames!think!ephraim
From: ephraim@think.COM (Ephraim Vishniac)
Newsgroups: comp.sys.mac
Subject: Re: SE/30 SCSI question
Message-ID: <38068@think.UUCP>
Date: 29 Mar 89 15:01:56 GMT
References: <12101@reed.UUCP> <1082@lts.UUCP> <11317@ut-emx.UUCP> <88424@felix.UUCP> <2519@phred.UUCP> <424c763b.a590@mag.engin.umich.edu>
Sender: news@think.UUCP
Reply-To: ephraim@think.com (Ephraim Vishniac)
Organization: Thinking Machines Corporation, Cambridge MA, USA
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In article <424c763b.a590@mag.engin.umich.edu> billkatt@caen.engin.umich.edu (billkatt) writes:
>Old Jasmine 20's just plain don't conform to the SCSI spec.  It may not work
>if it is on the same bus as another SCSI drive (do you have an internal?)
 ...
>open up the Jasmine, throw out the Seagate ST-225N which is inside...

Since the ST-225N is the same drive that Apple was using at the time,
it's a bit rash to claim that it's non-conforming.  There was a
problem with multiple drives, but it was intolerant software, not
non-conforming hardware that made the problem.

The ST225N was (perhaps still is) slow to release the SCSI bus after
an operation.  Annoying as it is, that's perfectly conforming
behavior.  The problem arose when another operation on another drive
followed immediately.  The software would arbitrate for the bus, find
it busy, and give up.  It should have retried.

There was no problem with multiple ST225N's on the same bus, because
any driver for the ST225N had to handle this perfectly legal
condition.  This was true of Apple's driver and it was true of mine.
(It was not true of the buggy sample driver distributed by Apple and
used verbatim by some startups.)

(Dis)claimer: Jasmine used my driver from January '87 until Tim
Standing's DriveWare replaced it about a year and half later.  I was
never a Jasmine employee.  I'm not doing any work for them now, and I
don't expect that I ever will again.


Ephraim Vishniac  /  Internet: ephraim@think.com  / AppleLink: ThinkingCorp
Thinking Machines Corporation / 245 First Street / Cambridge, MA 02142-1214

	"Arlo Guthrie, it seems, has found what he was looking for:
		God, and the Macintosh." (Boston Globe)