TB, DTE and PER bit interaction

Tom Wicklund wicklund at intellistor.com
Wed Aug 24 08:40:31 PDT 1994


Gerry Houlder writes:
 > I can't point to wording on this either, but SCSI has always taken the view
 > that recovered data is always transferred - that is why the TB bit has wording
 > to limit its effect to unrecoverable errors only. If DTE says to terminate a
 > transfer due to a recoverable error, it should terminate after the recovered
 > block is transferred.

I asked about this at one of the SCSI-2 meetings about 5 years ago, in
particular in relation to the VERIFY command (which doesn't have a
DATA IN phase but still defines the DTE bit).

I was told a very literal reading of the DTE bit -- when DTE is set a
recovered error causes the data phase to stop immediately, with no
relation to what data is being transferred.

I suppose literally one could argue that the target could enter some
other phase (or disconnect), then continue the data phase.

Hopefully the clarification Mr. Milligan mentioned will improve this
description since the current meaning of the bit appears to be
useless.





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