Problems using NCR/Symbios 53c80.

Hayden Smith HSmith at
Fri Feb 8 08:20:02 PST 2002

* From the T10 Reflector (t10 at, posted by:
* Hayden Smith <HSmith at>

I'm hoping someone here will know the answer to this question.

I have a target device that uses the old NCR/Symbios 53c80 controller.  I am
having problems with arbitration/reselection when multiple devices (6 or 7)
are connected on the bus.  I am following the flow chart detailed in the
specification but this doesn't seem to work correctly.  I am using a SCSI
bus analyzer to monitor the bus. I see large blocks of Bus Free and Arb.
This only appears to happen when disconnection is allowed and multiple
targets have disconnected at the same time.

Are there any app notes for the 53c80 that detail an improved procedure for
arbitration/reselection?  Are there any known bugs in the 53c80 in this
Better yet can anyone post me a piece of proven target code for the 53c80
that works for Bus Free/Arbitration/Reselection?

Any other idea's?

Thank you,
Hayden Smith.

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