Xref: utzoo comp.unix.aux:566 comp.sys.mac:24694 comp.periphs:1438
Path: utzoo!attcan!uunet!ncrlnk!ncrwic!encad!entec!jlohmeye
From: jlohmeye@entec.Wichita.NCR.COM (John Lohmeyer)
Newsgroups: comp.unix.aux,comp.sys.mac,comp.periphs
Subject: Re: A/UX generic SCSI driver and Syquest 44Mb removable drives
Keywords: A/UX SCSI driver Syquest
Message-ID: <310@entec.Wichita.NCR.COM>
Date: 5 Jan 89 01:17:34 GMT
References: <4370@portia.stanford.edu> <40443764.1285f@maize.engin.umich.edu> <eakdo#+=michael@xanadu.COM> <368@siswat.UUCP>
Reply-To: jlohmeye@entec.UUCP (John Lohmeyer)
Followup-To: comp.periphs
Organization: NCR Corporation, Wichita, Kansas
Lines: 16

In article <368@siswat.UUCP> buck@siswat.UUCP (A. Lester Buck) writes:
>In SCSI, the action of saving pointers means at least that much
>data is, in the target's opinion, error free.
>
Lester, actually saving the pointers means that the target probably doesn't
intend to re-transmit the data up to that point.  But it could if both the 
Host Adapter and the Target have implemented the MODIFY DATA POINTER message.
In any case, the host really doesn't know that the data is "error free" until
it receives GOOD status.  A target may transmit erroneous data and THEN tell
the host that the data is bad.

Some people have implemented host designs that assume all data sent prior to
a SAVE DATA POINTER message is "good" data -- they will probably get burned
some day...

John Lohmeyer      J.Lohmeyer@Wichita.NCR.COM