X3T9.2/88-026 Rev 0

To: X3T9.2 Committee (SCSI)   

From: Gerry Houlder   MPI/CDC

Subject: Proposed wording for new Unit Attention Conditions

This proposal is in response to an action item assigned to me at 
the Jan. 6-8 Working Group Meeting.  The proposed wording is 
intended to resolve 2 of the 4 "square bracket" notes on page 6-2 
of the Rev. 3 SCSI-2 draft.  It may not resolve the note stating 
that Gary Stephens has issues with this section or the note that 
removable media devices need START/STOP with LoEj set to pass 
through unit attention.

Replace the entire first paragraph of section 6.1.3 with the 
following:

"A unit attention condition shall begin for each initiator 
whenever the target has been reset by a BUS DEVICE RESET message, 
a "hard" RESET condition, or a power-on reset.  The target may 
(depending upon target device type and implementation of certain 
options) also set a unit attention condition for any of the 
following conditions:
  (1) a removable medium may have been changed;
  (2) MODE SELECT parameters in effect for this initiator have 
been changed by another initiator;
  (3) a new version or level of microcode has been installed in 
the target;
  (4) tagged commands queued for this initiator were cleared by 
another initiator;
  (5) INQUIRY data has changed.
The unit attention condition shall persist for each initiator 
until that initiator clears the condition from the logical unit 
as described in the following paragraphs."

When new proposals are received that create new unit attention 
condition possibilities, these possibilities should be added to 
the enumerated list.  I believe this wording satisfies the 
concerns behind the "square bracket" notes and should be accepted 
for Rev. 4 of the SCSI-2 draft.