Subject: Re: ZIP Drive problems
To: Mike Sienicki <mike@cpdist.com>
From: Leo Weppelman <leo@wau.mis.ah.nl>
List: port-atari
Date: 11/19/1998 16:37:48
Hi Mike. Glad your drive works ;-)

I'd like to add a few notes to your story...

I am missing:
  Step 1a: Check the system logs... The output of dmesg(1) helped a lot in
           diagnosing the problem area...

On Tue 17 Nov 1998, Mike Sienicki wrote:

[ ... ]
> Step #3  On V1.3H (or possibly other kernel versions), you may want to edit
> the scsiconf.c file to get rid of junk lun's.  Again, here is a quote from

I think you can say:  V1.3H or earlier. This piece needs some more fleshing
out. The problem might be restricted to the "IOMEGA, ZIP 100, J.03".
                                                              ^^^^
I will mail you later about this - like to get this fixed.

[ ... ]
> Step #4  If you see a line in your bootup messages that looks like this:
>          "sd1(ncrscsi0:1:0): Does not support linked commands"
> then take the advice of an expert and:
> 
> >This might be another pitfall... Try setting TRY_SCSI_LINKED_COMMANDS to
> >0x7d (ie. disable _all_ linked commands for target 1).

In retrospect, your ZIP might be working without changing this... Let me
try to explain it as a FAQ entry:

  3.3 What does "Does not support linked commands" mean

      Linked commands is a method of chaining SCSI commands to each other.
      Usage of linked commands might be slightly faster on the SCSI-bus
      because the target selection phase can be omitted between linked
      commands.  Some of the older SCSI devices are not capable of
      handling linked commands, some devices even choke on them...

      To allow mixing older and newer devices, the atari SCSI-driver can
      be told explicitely to _never_ use linked commands on a target. This
      is done with the compile-time option 'TRY_SCSI_LINKED_COMMANDS'.
      This is a bit mask. A zero bit means: 'never use linked commands on
      this target'. A one bit means: 'try a linked command when appropriate,
      if the target gives an error on it, never try it again'.
      Another possibility is not to define this option at all, this will
      tell the SCSI-driver not to use linked commands at all.

      Oh, bits are numbered from right to left. Excluding target 0 gives
      a mask of 0xfe. Normally, target 8 (the host adapter == interface)
      is also excluded, giving: 0x7e.

Leo.