A/UX generic SCSI driver and Syquest 44Mb removable drives

John Lohmeyer jlohmeye at entec.Wichita.NCR.COM
Thu Jan 5 11:17:34 AEST 1989


In article <368 at siswat.UUCP> buck at 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 at Wichita.NCR.COM



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