Summary of responses for enabling Sync SCSI on SS1

From: Bala Vasireddi (
Date: Fri Jul 13 1990 - 19:59:27 CDT

My Original question:

   Can somebody explain how we can enable Synchronous SCSI on a SS1 running
   OS 4.0.3c. Also can you please explain if we have to change any
   jumpers/settings on the Quantum 105 disk internal disk drives (that come with
   the SS1) to make them Synchronous.

   Please mail your responses to me, and I'll summarize.


  You can enable sync SCSI on an SS1,SS1+,SLC by un-commenting the
  'SCSI_OPTIONS_SYNC' line in /sys/scsi/conf/scsi_confdata.c
  and building the new kernel.

  To enable this in the vmunix do the following:

  adb -k -w /vmunix /dev/mem
  scsi_options/X ; should show 18
  ./W 38 ; changes only the running kernel
  .?W 38 ; changes /vmunix for all of time :-)

  You don't need to change any jumpers on the Quantum 105S disk to enable
  sync SCSI.

  More than one user recommended that, if you want to enable the sync SCSI
  you should make sure that you have a SCSI cable that is "short and clean".
  If you have an external drive AND one or two internals you may very well run
  into problems (I'm not sure they'll be *real* problems, you may just get
  occasional SCSI errors).

  I myself have seen the following messages after enabling sync SCSI on my SS1+
  which has an internal Quantum and an external Micropolis 327MB disk drive:

  sd0: SCSI transport failed: reason 'reset': retrying command

  But, without any apparent side-effects.


From: (Kurt J. Lidl)
From: Fons Ullings <>
From: dgsi!brian (Brian Kelley/1000000)
From: (Sam Fulcomer)

Thanks again for all the help.

Bala Vasireddi,            Phone: (415)962-5036
Synopsys, Inc.             FAX:   (415)965-8637
1098 Alta Ave              DDN:
Mountain View, CA 94043    UUCP:  ..!!synopsys!bala

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